Laminates of polymers having perfluorocyclobutane rings and polymers containing perfluorocyclobutane rings

ABSTRACT

A laminate has at least two layers, at least one of which comprises a polymer having more than one perfluorocyclobutane group. Such polymers impart qualities of enviornmental or protection, chemical and solvent resistance, hydrolytic stability, lubricity, low dielectric, hydrostatic stability, weatherability, flame resistance, chemical resistance, hydrolytic stability, lubricity, environmental protection, scratch resistance, solvent resistance, surface passivation, water repellancy, lower surface refractive index, lower surface coefficient of friction, fluid barrier properties, oil repellancy, thermal stability, and/or reduced moisture pick-up. Additionally, the coatings are optically clear, easy to apply either neat, in a solvent or otherwise, have relatively low cure temperatures for their temperature resistance, and exhibit insulating and planarizing capabilities.

This invention relates to laminates of polymers containing more than oneperfluorocyclobutane ring.

Laminates are materials having more than one layer. While in thesimplest form a laminate has mutually coextensive discrete layers, theterm also includes layered materials wherein one or more layers may havedimensions different from at least one other layer. For instance, amiddle layer of three layers may extend beyond the edges of the othertwo layers or one or more of the other layers may extend beyond theedges of the middle layer. Also, layers may not remain discrete afterformation of a laminate. For instance, in a laminate of three layers, amiddle layer may be discontinuous, e.g. a loosely woven material, andlayers contiguous thereto may be of the same or miscible compositionssuch that in a lamination process, those layers merge throughdiscontinuities in the middle layer. Laminates also include coatedobjects wherein one layer may cover all or substantially all surfaces ofanother layer or wherein what may be considered layers above and belowan object may join in at least one place or along one or more edges.Laminates in their simplest form have relatively planar layers, but theterm includes non-planar materials of any shape including wires, fibers,pipes, tubes, bowls, pots, spheres, cubes, bricks, irregularly shapedobjects, discontinuous materials and the like.

A wide variety of laminates are known. Their properties and uses dependon the materials used for the layers. While laminates having layers ofpolymers are often formed and useful for the properties of the polymers,polymers seldom have high temperature resistance, fire retardancy andother properties that would be desirable in laminates.

SUMMARY OF THE INVENTION

Polymers having more than one perfluorocyclobutane group have recentlybeen discovered and include polymers thermally formed from monomershaving at least two perfluorovinyl groups and interpolymers of compoundshaving at least one perfluorocyclobutane ring and at least twofunctional groups reactive with di- or poly- functional compounds toform polymers.

The present invention, in one aspect, is a laminate having at least twolayers at least one of which comprises a polymer having more than oneperfluorocyclobutane group. Such laminates are particularly useful inelectronics, building materials, optics for applications requiring heator weather resistance and the like.

The crosslinked polymers exhibit enhanced solvent resistance andincreased mechanical strength, without loss of advantageous electricalproperties, such as low dielectric constant and dissipation factor.

The invention includes electronic devices and computers comprising suchlaminates.

In another aspect the invention includes a process of preparing alaminate comprising a step of coating at least one material with apolymer having more than one perfluorocyclobutane group. In yet anotheraspect, the invention includes a process for preparing a laminatecomprising adhering at least one layer of a polymer having more than oneperfluorocyclobutane group and at least one layer of a material having acomposition different from the polymer.

DETAILED DESCRIPTION OF THE INVENTION

Laminates of the invention have at least two layers, at least one ofwhich is a polymer having perfluorocyclobutane rings. The other layer(s)are any material, preferably at least one layer is a material havingproperties, preferably physical or chemical properties different fromthe layer having perfluorocyclobutane rings. More preferably theproperties are such that the layer(s) of polymer improves at least oneproperty of the laminate relative to the properties of the rest of thelaminate without the polymer layer(s). For instance, a layer of polymermay be added to effect, preferably to improve, passivity, mechanicalstrength, flame retardancy, smoothing or planarity, receiving an image,selective removal, hydrolytic stability, moisture resistance, chemicalresistance, heat resistance, weatherabitily, low dielectric nature(insulating),wear resistance, scratch resistance.

The layer(s) other than the layer(s) of polymer havingperfluorocyclobutane rings are suitably such materials as wood, metal,ceramics, glass, other polymers, paper, paper board cloth, woven fibers,nonwoven fiber mats, synthetic fibers, Kevlar™, carbon fibers, siliconand other inorganic substrates and the like. The materials selected forthe layers depend on the desired application. Preferred materialsinclude glass, including glass fibers (woven, non-woven or strands),ceramics such as metals such as Al (aluminum), Mg (magnesium), Ti(titanium), Cu (copper), Cr (chromium), Au (gold), Ag (silver), W(tungsten), stainless steel, Hastalloy, carbon steel and polymers suchas epoxy resins, polyimides, benzocyclobutane polymers, otherthermosets, and the like and polystyrene, polyamides, polycarbonates,polyesters and other thermoplastics. Optionally, the other layer(s) mayinclude at least one layer of polymer containing perfluorocyclobutanerings, said layer(s) preferably having a different composition, forinstance different in polymer structure, molecular weight, additives,crosslinking type or density.

It should be noted that the layer(s) other than at least one of apolymer having perfluorocyclobutane rings can be of any shape, generallydetermined by the purpose of the laminate. For instance, the otherlayer(s) are suitably disks, plates, wires, tubes, boards, spheres,rods, pipes, cylindrical, bricks, fibers, woven or non-woven fabrics,yarns including comingled yarns, ordered polymers, woven or non wovenmat. In each case the shape is optionally, hollow or solid, in the caseof hollow objects, the polymer layer(s) is optionally inside and/oroutside. The other layer is optionally porous such that the polymerlayer(s) penetrate, such as graphite mat or fabric, glass mat or fabric,a scrim, particulate material and the like.

Laminates of the invention have at least one layer of polymer having atleast two perfluorocyclobutane rings. Such polymers and the methods ofmaking them and monomers useful in their preparation are disclosed inU.S. application Ser. Nos. 364,667, 364,666, 364,686, 364,665, all filedJun. 9, 1989 (now U.S. Pat. Nos. 5,037,917; 5,037,919; 5,021,602;5,023,380); U.S. application Ser. No.534,819 filed Jun. 7,1990 (now U.S.Pat. No. 5,066,746); U.S. application Ser. No. 451,404 filed Dec. 15,1989 (now U.S. Pat. No. 5,037,918) which are incorporated herein byreference with respect to the preparation of monomers and polymersuseful in the practice of the present invention.

Preferably, polymers used in the practice of the invention are formed bythermal reaction of monomers, including oligomers or low molecularweight polymers, having at least two dimerizable perfluorovinyl groupssuch that perfluorocyclobutane groups are formed. A dimerizableperfluorovinyl group is a perfluorovinyl group which reacts with anothersuch group to form a perfluorocyclobutane ring. Alternatively, thepolymers are prepared by reacting monomers having at least oneperfluorocyclobutane ring and at least two functional groups reactivewith di- or poly-functional compounds to form interpolymers therewith.

Properties of the polymers vary with the proportion ofperfluorocyclobutane rings, the nature of other portions of the polymerand other chemical and structural features of the polymers. Forinstance, the relative proportion by weight of the perfluorocyclobutanegroups to the other molecular components of the resulting products canvary over a wide range of from 12 to 1 to 0.01 to 1, preferably from 5to 1 to 0.02 to 1 and most preferably from 2 to 1 to 0.03 to 1. Highproportions of perfluorocyclobutane groups, preferably at least about0.1 to 1 more preferably at least about 0.25 to 1 are desirable forinstance, when fluorocarbon character such as low dielectric constant isbeneficial in the products. Exemplary of such products are lowdielectric fluids and lubricants. Medium ranges of ratios of weights ofperfluorocyclobutane groups to other molecular structures of 2 to 1 to 1to 4 are desirable, for instance, when higher physical strength andrelatively lower dielectric constants (for example, relative toconventional engineering thermoplastics) are desired, for example, inlow dielectric plastics. These relatively low dielectric plastics areparticularly preferred and are preferably achieved by using aromaticcompounds substituted with trifluorovinyl groups, most preferably, withtrifluorovinyl ether groups. Very low proportions of theperfluorocyclobutane groups result, for instance, when low molecularweight oligomers (for example, in the range of 1000 to 20,000) areterminated by trifluorovinyl groups and then thermally dimerized to formhigher molecular weight polymers.

Any monomer having at least two dimerizable perfluorovinyl groups issuitably used to form polymers used in the practice of the presentinvention.

In the thermal polymerization of diperfluorovinyl compounds,substantially linear polymers having little branching are believed to beformed. In the practice of some embodiments of the present invention, itis preferred to crosslink such polymers to achieve properties such asimproved (relative to the uncrosslinked polymer) mechanical strength,solvent resistance, hydrolytic stability, thermal stability, and/or wearresistance. At least two types of crosslinking are observed. A firsttype of crosslinking involves the use of monomers having at least threeperfluorovinyl groups; such crosslinking is referred to herein as"polyfunctional crosslinking." A second type of crosslinking is observedwhen certain types of monomers are used, and because it is believed thatthis second type of crosslinking involves certain aromatic structures inthe backbone of the polymer, it is referred to herein as "backbonecrosslinking."

Without crosslinking, solid polymers useful in the invention aregenerally thermoplastic except in the case of partially polymerizedmonomers which are referred to herein as prepolymers or B-stagedpolymers, which may be partially crosslinked and/or not thermoplastic.Viscosity of either a melt or solution of the polymer increases ascrosslinking occurs until the gel point and resulting insolubility isreached. Backbone crosslinked polymers are preferably elastomeric, thatis, the polymer can generally regain its shape after deformation. Thatdeformation is indicated by elongation measurements greater than about100 percent at temperatures above the glass transition temperature (Tg)of the polymer. Backbone crosslinked polymers preferably retain theirelastomeric properties at temperatures of from their glass transitiontemperatures to the temperatures at which they are observed to degrade,preferably about 400° C. The glass transition temperature varies withthe composition of the polymer.

Backbone crosslinking also increases a polymer's tensile strength asmeasured by the procedures of ASTM D882-83. The increase is preferablyup to 1000 percent, more preferably from 10 percent to 500 percent, mostpreferably of from 10 percent to 100 percent increase. Also thepolymer's tensile and flexural modulus as measured by the procedures ofASTM D882-83 and ASTM D790-81, respectively, also increases, preferablyup to 1000 percent, more preferably of from 10 percent to 500 percent,most preferably of from 10 percent to 100 percent. Additionally, thefluorine-containing structures of such crosslinked polymers preferablyretain relatively low dielectric constants.

Such properties are useful in laminates such as disk substrates, mediabinders, optical waveguides, fiber bundles, circuit boards, opticalcladding, encapsulated objects and the like.

Although any monomer having two dimerizable perfluorovinyl groups andwhich is crosslinkable is suitably used for backbone crosslinking,polymers used in the invention are preferably prepared from monomershaving two perfluorovinyl groups separated by at least one hydrocarbylgroup having at least one carbon atom between the perfluorovinyl groups.The polymer preferably has a backbone comprising perfluorocyclobutanegroups, linking structures and hydrocarbon containing groups.

When the perfluorovinyl groups are attached to aliphatic carbons orseparated from aliphatic carbons by single atoms such as oxygen, theperfluorovinyl groups are preferably primary or secondary. Preferably,to avoid rearrangement and facilitate polymer formation and crosslinkingthe monomers have structures such that resulting polymers havehydrocarbyl groups (preferably aromatic rings), perfluorocyclobutanerings and at least one non-carbon atom such as oxygen, silicon, boron,phosphorus, nitrogen, selenium, tellurium and/or sulfur atom (eachoptionally substituted) in the backbones.

The monomers preferably have a structure represented by the followingFormula I:

Formula I

    CF.sub.2 ═CF--X--R--(X--CF═CF.sub.2).sub.m

wherein R represents an, optionally inertly substituted group; each X isindependently a bond or any group which links R and a perfluorovinylgroup (hereinafter linking structures), said structures being inert; m+1is the number of --X--CF═CF₂ units. Advantageously, m is an integer offrom 1 to 3, preferably from 1 to 2. While compounds represented byFormula I wherein m is one are especially useful for forming linearpolymers, compounds wherein m is 2 or more particularly 2 or 3 areespecially useful for polyfunctional crosslinking. By "inert" it ismeant that the structures or substituents do not react undesirably withperfluorovinyl groups or interfere undesirably with polymerization(perfluorocyclobutane formation) of the monomers.

Linking structures X are each independently a linking structure such asa bond, an oxygen atom, carboxylic and thiocarboxylic ester groups,other sulfur containing structures, perfluoroalkylene,perfluoroalkylen:e ether, alkylene, acetylene, phosphorus containinggroups such as phosphines, carbonyl and thiocarbonyl groups; seleno:telluro: nitrido; silicon-containing groups such as silanediyl,trisilanediyl tetrasilanetetrayl, siloxanediyl, disiloxanediyl,trisiloxyl, trisilazanyl, or silylthio groups; boron-containing groupssuch as boranediyl or methylboranediyl groups; a combination thereof, orany other group which is inert, which molecularly links R to aperfluorovinyl group, and which provides a molecular structure in whichthe perfluorovinyl group is sufficiently reactive to form aperfluorocyclobutane ring. For instance, X is preferably other than aperfluoroalkylene group because perfluorovinyl groups attached toperfluoroalkylene groups generally require temperatures greater thanabout 300° C. to dimerize and are subject to isomerization.

It is preferred that at least one of X is not a bond. More preferably, Xis independently selected from the group consisting of groups having atleast one noncarbon atom between the perfluorovinyl groups and R, suchas groups containing oxygen, sulfur, selenium atoms, tellurium atoms,silicon, boron, phosphorus or nitrogen between R and the perfluorovinylgroup, for example, oxygen atoms, sulfur atoms, (thio) carboxylic estergroups, phosphines, (thio) carbonyl groups, seleno, telluro, silanediyl,trisilanediyl, trisilazanyl or silylthio, boranediyl groups. Preferredgroups have S, O, Si, N or P, more preferably S, O, or Si between R andthe perfluorovinyl group, such as carbonyl, thiocarbonyl, sulfone,sulfoxy, silanediyl, amines (optionally inertly substituted), oxygen orsulfur atoms. Most preferably there is a single atom other than carbonbetween R and each perfluorovinyl group: even more preferably the singleatom is oxygen or sulfur, among those groups preferably an ether orsulfide linkage, because monomers having such linking structuresadvantageously form perfluorocyclobutane groups at lower temperaturesthan are needed with such groups as perfluoroalkyl groups and are morestable than monomers where the perfluorovinyl group is attached directlyto R, particularly when R is aromatic. Monomers having such linkingstructures are also relatively easily prepared.

R is suitably any inert molecular structure, preferably a molecularstructure which facilitates formation of perfluorocyclobutane ringsand/or polyfunctional crosslinking and/or imparts desirable physicalproperties to polymers or oligomers prepared from the monomers. For thepurpose of imparting desirable physical properties to polymers, Rpreferably contains at least one carbon atom. Preferably, the carbonatom is in the molecular chain between X's because monomers having atleast one carbon atom between X's when X is other than a bond, tend tohave desirable stability and to produce polymers having desirablephysical properties. Alternatively, the carbon atom is in a side chain:for instance, --R-- can be --N(CH₃)--, --N(CH₂ CH₃)--, --P(CH₃)-- or--P(CH₂ CH₃)--. The carbon atoms(s) in R are suitably in aliphatic,cycloaliphatic, aromatic, heterocyclic groups or combinations thereof.Additionally, R optionally contains groups or has substituents which areinert, that is which do not undesirably interfere with the formation ofperfluorocyclobutane rings from perfluorovinyl groups. Inertsubstituents include ether, carbonyl, ester, tertiary amide, carbonate,sulfide, sulfoxide, sulfone, nitrile, alkyl phosphonate, tertiary amine,alkyl phosphate, alkyl silyl, chlorine, bromine, fluorine, alkyl,arylalkyl, alkylaryl, cycloalkyl, aromatic, heterocyclic, alkoxyl andaryloxy groups, which inert substituents are suitably in any position,for instance, in a polymer backbone between X's and/or appended to sucha backbone. Carbon-containing inert substituents on R preferably containfrom 1 to 50, more preferably from 1 to 12 carbon atoms because of thestability and ease of working with monomers of lower molecular weight.R, including inert substituents preferably has a molecular weight (MW)of from 14 to 20,000, more preferably from 75 to 15,000 and mostpreferably from 75 to 5,000. These ranges include monomeric andoligomeric R groups. In the case of monomers which are other thanoligomeric, R preferably has from 1 to 50, more preferably from 6 to 50,carbon atoms because molecular weights above this reduce thecontribution to properties made by the fluorine-containing substituentswhen R is alkyl or aromatic hydrocarbon. As previously discussed, thenature of R as well as the perfluorocyclobutane content of the polymerscan vary broadly according to the type of products desired.

Preferably, for polymers having good plastic properties such as tensilestrength and flexibility, at least one carbon atom of R is in themolecular chain between X's and is part of an aromatic nucleus. Aromaticgroups are desirable because of improved physical properties of thepolymers and ease of manufacture of the monomers. For both ease ofmanufacture of the monomer and monomer stability, when R is aromatic,each X is preferably independently sulfur or oxygen. The aromatic groupcan be any molecular structure having aromatic character, advantageouslyhaving at least one six-membered aromatic ring, suitably having anynumber of such six-membered rings fused together or connected by bondsor linking structures. R preferably has from 1 to 50 such rings, morepreferably from 1 to 10 rings, more preferably containing from 6 to 25carbon atoms, most preferably R has at least 2 to 4 aromatic rings toimpart properties such as hardness and/or stiffness to a polymer. Thearomatic fragment is suitably unsubstituted or inertly substituted.Inert substituents on an aromatic R include, for instance, the inertsubstituents listed for R generally. Exemplary aromatic molecularfragments include, for instance, perchlorophenylene, phenylene,biphenylene, naphthylene, dichlorophenylene, nitrophenylene,p,p'(2,2-diphenylene propane) [--C₆ H₄ --C(CH₃)₂ --C₆ H₄ --];p,p'-(2,2-diphenylene1,1,1,3,3,3 hexafluoropropane) [--C₆ H₄ --C(CF₃)₂--C₆ H₄ --], preferably biphenylene; phenylene; 9,9'-diphenylfluorene,oxydiphenylene; thiodiphenylene; 1,1,1-triphenyleneethane;1,3,5-triphenylenebenzene; 1,3,5-(2-phenylene-2-propyl)benzene;1,1,1-triphenylenemethane; 1,1,2,2-tetraphenylene-1,2-diphenylethane;bis(1,1-diphenyleneethyl)benzene;1-(2-phenylene-2-propyl)-4-(1,1-diphenyleneethyl)benzene;2,2-diphenylene propane; 2,2'-diphenylene,1,1,1,3,3,3-hexafluoropropane: 1,1-diphenylene-1-phenylethane;naphthalene: and anthracene. Molecular weights of aromatic ringcontaining polymers are preferably at least about 10,000. Such aromaticgroups are preferably present because they generally impart hightemperature glass transition properties (Tg) and good mechanicalstrength (for example, as measured by differential scanning calorimetry(DSC) and tensile/flexural tests) to the polymer.

Such properties are preferred for laminates such as circuit boards,optical waveguides, and the like.

For the purpose of facilitating backbone crosslinking, more preferably,R is a group which reacts with perfluorovinyl groups residual in asubstantially linear polymer to form a crosslinked or branched molecularstructure. The reaction of R with the perfluorovinyl groups is suitablyinitiated by heat, free radicals, wave energy, or any other crosslinkinginitiating means, but preferably by heat. Most preferably R includes astructure having two double, triple or aromatic bonds (hereaftermultiple bonds) separated by a single bond and capable of attaining acisoid conformation. Such structures are recognized in the art as latentDiels-Alder dienes. Preferably the latent dienes are suitable forreactions of the Diels-Alder type, more preferably suitable for suchreactions with perfluorovinyl groups in the monomers, most preferablysuitable for such reactions with perfluorovinyl ether groups underconditions used for crosslinking. The single bond is preferably a carbonto carbon single bond. Each of the multiple bonds is independentlysuitably a multiple bond between any two atoms, preferably between acarbon atom and any other atom (for example, --C═O, --C═C--, --C.tbd.N),more preferably a carbon to carbon bond. Exemplary of preferred R groupsinclude, for instance, biphenylene, 9,9'-diphenylfluorene, fluorene,cyclopentadienylene, furan and anthracene.

Most preferably, at least one aromatic carbon atom of R is bondeddirectly to X, most preferably aromatic carbon atoms of R are bondeddirectly to each X because perfluorovinyl groups bonded to X, said Xbeing bonded to aromatic groups are generally more reactive in formingperfluorocyclobutane rings.

Some specific combinations of X and R are especially preferred: when Ris aromatic, at least one X is preferably other than a bond, morepreferably neither X is a bond, because attachment of perfluorovinylgroups directly to aromatic R renders the perfluorovinyl groups morethermally and oxidatively unstable than when said groups are attached,for instance to oxygen or sulfur. When R is a perfluoroalkyl group or aperfluoroalkylether group, at least one X is preferably other than abond, most preferably no X is a bond or a perfluoroalkyl group, becauseperfluorovinyl groups linked directly to perfluoroalkyl groups requiretemperature in excess of about 300° C. to dimerize and are subject toisomerization.

Monomers preferred for use in preparing polymers useful in the practiceof the present invention are suitably prepared by any method which linksmolecular structures having perfluorovinyl groups to other molecularstructures or which forms perfluorovinyl groups.

An exemplary method of preparing a trisperfluorovinyl ether (exemplaryof monomers having more than one perfluorovinyl group) is illustrated bya process having the following steps:

(A) A trihydroxy compound such as 1,1,1-tris(4-hydroxyphenyl)ethane isconverted to its sodium or potassium salt in a solvent such as water,methanol or a mixture thereof. The methanol or another solvent for thetrihydroxy compound is used when the compound is not water soluble, tokeep the trihydroxy compound in solution. Salt formation occursconveniently at from about 0° C. to about 120° C. at atmosphericpressure, preferably under a nitrogen atmosphere to avoid oxidation inthe case of an oxidizable trihydroxy compound.

(B) When methanol or other solvent other than water is used, it isremoved, e.g. under reduced pressure at any convenient temperature andpressure with replacement of water as it is lost.

(C) The salt is dried and powdered by means within the skill in the artfor example, in a drum dryer or other apparatus which provides agitationand water removal, e.g. by heat and/or reduced pressure. A dryness ofless than about 1 weight percent water, preferably less than about 0.1percent, more preferably less than about 0.02 weight percent ispreferably attained in this step. If such dryness is not attained inthis step, step E is alternatively used to attain said dryness.

(D) The salt is slurried in a polar, aprotic solvent suitable forachieving reaction such as DMSO (dimethyl sulfoxide), ethers, DMF(dimethyl formamide), HMPA (hexamethylphosphoramide), diglyme,tetraglyme or glyme.

(E) If dryness to less than about 1 weight percent water is not attainedin step (C), an aprotic azeotropic medium such as toluene orchlorobenzene in a solvent to azeotrope medium ratio of from about 10 to1 to about 1.5 to 1 is added, and the solution dried by the azeotropicremoval of water. About half of the azeotropeic medium is removed, forexample, by distillation, and the mixture is cooled below about 50° C.,preferably below about 20° C.

(F) A dihalotetrafluoroethane such as 1,2-dibromotetrafluoroethane isadded to form a mixture as the reaction temperature is controlled at atemperature suitable for the reaction to occur substantially without theside reaction of aromatic ring halogenation; in the case of1,1,1-tris(4-hydroxyphenyl)ethane a temperature preferably below about20° C. is used initially. The mixture is stirred at e.g. 18° C. to 25°C., preferably until the amount (yield) of product stops increasing (thereaction is complete) as indicated by gas chromatographic analysis ofproduct tris-bromide.

(G) The tris-bromide is purified by means within the skill in the art:

(G1) For instance, the mixture is poured into about an equal volume ofcold water, conveniently from about 0.5 to about 3 times the volume ofthe solution, and the product falls out as the lower layer. There ispreferably sufficient cooling to offset the heat generated by admixingDMSO (or other solvent) and water. The product, a tris-bromide, is thendistilled, for example, at 190° C. to 195° C./0.05 mm Hg. Whentrisbromides are heat stable as observed in the case of1,1,1-tris(4-(2-bromotrifluoroethoxy)phenyl)ethane, the degree of vacuumis selected to give a convenient boiling point. Such selection is withinthe skill in the art.

(G2) Alternatively, the solution of product is extracted with anon-polar solvent such as a hydrocarbon, for instance hexane, usingmeans within the skill in the art such as countercurrent extraction. Thesolvent is conveniently used in an amount of from about 1 to about 5times the volume of solution of product, and the product is extractedinto the hydrocarbon. The hydrocarbon is then removed by means withinthe skill in the art such as evaporation, conveniently under reducedpressure.

(H) The tris-bromide is used directly or, if desired, in cases where thetris-bromide is a solid it may be dissolved for ease of addition in apolar, aprotic solvent such as diglyme, tetraglyme, glyme, or a nitrilesuch as acetonitrile, glutaronitrile, or 3-methoxypropionitrile andadded to a hot (for example 40°-135° C.) mixture of the same solvent andgranular zinc to form the tris-perfluorovinyl ether (TVE).Alternatively, the tris-bromide can be added to a hot (for example 120°C.) mixture of, for example, diglyme or nitrile and granular zinc as amelt without dilution if heated above its melting point, for example toabout 120° C. in the case of1,1,1-tris(4-(2bromotrifluoroethoxy)phenyl)ethane. Temperatures aboveabout 135° C. are preferably avoided to avoid dimerization ofperfluorovinyl groups.

(I) The TVE is isolated by removing the zinc salts for example; bycentrifugation, evaporating the diglyme under reduced pressure, dilutingthe TVE with a, preferably low boiling, solvent such as hexane, andflushing the solution through a pad of neutral alumina or otherabsorbent for color bodies and residual ionic species. Alternatively,the zinc salts are removed by filtration and the TVE distilled undervacuum, for example in two stages, the first to remove solvent and thesecond to purify the TVE. Preferably, temperatures above about 110° C.are avoided to avoid dimerization of perfluorovinyl groups. Especiallywhen a very pure product is desired, these methods of purification aresuitably combined.

Alternatively, the TVE is isolated by removing the zinc salts byfiltration, evaporating the glyme (if used) under reduced pressure,diluting the TVE or its solution in a nitrile with hydrocarbon solventfor the TVE such as hexane and purifying by countercurrent extraction orsimilarly extracting the hydrocarbon with polar organic materials suchas acetonitrile or DMSO. The pure TVE in hydrocarbon is then flushedthrough a pad of absorbent for color bodies and residual ionic speciessuch as decolorizing carbon, ion exchange resins, alumina or the like.

(J) The hexane or other hydrocarbon, if used, is removed from the TVEe.g. by evaporation under reduced pressure.

Polymers produced from the preferred monomers preferably have a formularepresented by the following Formula II:

Formula II

    --[X--R--[X--Q].sub.m ].sub.n --

wherein R, X, and m, are defined above, Q is a perfluorocyclobutanegroup; and n is an integer representing the number of repeating units,which is preferably from 2 to 100,000. More preferably from 2 to 10,000,most preferably from 3 to 5,000. More preferably m is one or two.Formula II is generalized; when m is greater than one, some of the --X--Q structures represent branching and/or crosslinking.

The monomers are heated to a temperature and for a time sufficient toform perfluorocyclobutane rings. Temperatures suitable for formingperfluorocyclobutane rings differ with the structure of the monomer. Ingeneral, temperatures above about 40° C. are suitable for formation ofperfluorocyclobutane rings, preferably the temperature is above about50° C., more preferably above about 100° C., because these temperaturesresult in formation of the rings at successively faster rates.Temperatures above about 450° C. are preferably avoided becauseperfluorocyclobutane groups are generally thermally unstable above suchtemperatures.

Monomers having three or more dimerizable perfluorovinyl groups(hereinafter referred to as polyfunctional) are especially useful toform polymers having relatively high Tg believed to be due topolyfunctional crosslinking. From 0 to 100 percent by weight of suchmonomers are suitably used, preferably sufficient of the monomers havingat least three perfluorovinyl groups to measurably increase the chemicalresistance and/or mechanical strength of the polymer over that of apolymer of monomers having corresponding structures but with only twoperfluorovinyl groups, more preferably at least about 0.05 mole percent,most preferably from 0.1 to 100 mole percent of such monomers is used.While use of lower proportions of polyfunctional monomer(s) produces,generally thermoplastic, polymers having crosslinking and correspondingproperties of toughness and solvent resistance, use of sufficientpolyfunctional monomers to form thermosetting polymers is useful toproduce crosslinked polymers having greater chemical resistance and/ormechanical strength. The relative proportions of polyfunctional monomerwhich produce such polymers varies with the structure of the monomers.However, from 0.5 to 75 mole percent polyfunctional monomers used withmonomers having 2 perfluorovinyl groups is sufficient to result insufficient crosslinking in a thermoplastic polymer to reduce itssolubility in a solvent.

More than one stage of polymerization is often advantageous particularlyfor polyfunctional monomers, to achieve desired viscosity for forminglaminates. A first stage of polymerization is conveniently carried outat temperatures of from 50° C. to 400° C., preferably from 105° C. to250° C., more preferably from 120° C. to 170° C. At least one laterstage follows the first stage and is preferably carried out at a highertemperature than the first to allow the polymerization to proceed towardcompletion. Such later stage(s) are conveniently carried out attemperatures from that sufficient to result in additional polymerizationup to the decomposition temperature of a resulting polymer, preferablyfrom 100° C. to 450° C., preferably from 120° C. to 400° C., morepreferably from 200° C. to 375° C. Those skilled in the art willrecognize that the first and later stages can represent more than onestage or can be carried out using two or more temperatures and that aseries of stages or a continuum of temperatures are suitably used. Inaddition to these stages a postcure at relative high temperature such asfrom 200° C. to 450° C. is optionally used. The postcure is suitably forany duration sufficient to change physical properties and insufficientto decompose the polymer, preferably from 1 minute to 1 week, morepreferably at high temperatures such as from 240° C. to 450° C. forduration of from 1 minute to 24 hours. Stages of polymerization areconveniently run under conditions previously described forpolymerization of the monomers. When a solvent is used in an earlystage, and it is desirable to avoid bubbles that may occur as a solventis driven off, advantageously the solvent is removed before or during alater stage.

It is found that solvent, degree of polymerization, and otherparameters, for instance conditions of coating, effect coating qualityand thickness. Those skilled in the art are able to determine optimumconditions for each particular polymer and coating desired. Anillustrative example with variations in solvent, degree ofpolymerization and parameters of spin coating is given in the Examplesof this invention.

Dielectric constants and static dissipation factors (as measuredaccording to the procedures of ASTM D150-87) preferably range from 2.2to 3.0 and from 0.0001 to 0.005 respectively. Glass transitiontemperatures increase from about ambient when R is phenyl, to about 170°C. when R is biphenyl, to about 230° C. when R is 9,9-diphenylfluorene,to about 286° C. or higher when R is 1,1,1-triphenylethane.

The linear polymers advantageously are cast from solvents such asethers, esters, aromatic hydrocarbons and chlorinated solvents,mesitylene, diglyme, o-xylene, n-butyl acetate, tetrahydrofuran ordichloromethane.

Before backbone crosslinking, substantially linear polymers or oligomersare thermally produced from the preferred monomers. The polymers can becrosslinked by any crosslinking initiating means such as by heat, byfree radicals, or by wave energy. Thermally backbone crosslinkedpolymers are prepared from such thermally formed polymers containingperfluorocyclobutane rings by heating the polymers to a temperaturesufficient to result in crosslinking, that is for chemical bonds to formbetween at least some of the polymer molecules. The temperature for suchcrosslinking is higher than that required for thermal (linear)polymerization, preferably it is at least about 50° C. degrees higherthan the temperature required for thermal (linear) polymerization, morepreferably from 250° C. to 400° C., most preferably from 280° C. to 380°C., even more preferably from 280° C. to 340° C. These temperatures aresuitably maintained for a time sufficient to achieve a preselecteddegree of crosslinking. Such times are preferably from 1 minute to 10days, more preferably from 15 minutes to 1 day (24 hours), mostpreferably from 15 minutes to 8 hours.

In alternative embodiments of the invention, the polymer is formed frommonomers having at least one perfluorocyclobutane ring, preferably ofthe formula: ##STR1## wherein R and R' independently representoptionally inertly substituted groups; X and X' represent molecularstructures which link R and R' with the perfluorocyclobutane ring: n andn' are the number of G and G' groups, respectively, and preferably areindependently integers of from 1 to about 4, more preferably from 1 toabout 2 most preferably 1; and G and G' independently represent anyreactive functional groups or any groups convertible into reactivefunctional groups, preferably any functional group suitable for reactionwith di- or poly-functional compounds to form polymers. Alternatively, Gand/or G' is a group suitable for chemical conversion into a functionalgroup suitable for reaction to form a polymer.

G and G' are preferably independently selected from the group consistingof reactive functional groups including hydroxyl groups (both alcoholicand phenolic) and esters thereof, carboxylic acid groups, thiocarboxylicacid groups, thiocarboxylic and carboxylic esters, preferably loweralkyl esters of from one to about 12 carbon atoms, such as methyl andethyl esters, acyl halides such as chlorides, isocyanates, acyl azides,acetyl groups, trihaloacetyl groups, primary or secondary amines,sulfide groups, sulfonic acid groups, sulfonamide groups, ketones,aldehydes, epoxy groups, primary or secondary amides, halo groups (e.g.chloro, bromo, iodo, and fluoro groups), nitro groups, cyano groups,anhydrides, imides, cyanate groups, vinyl, allyl, acetylene groups;silicon-containing substituents such as alkyl silanes, siloxanes,chlorosilanes, phosphorus-containing groups such as phosphines,phosphate, phosphonate, boron-containing groups such as boranes andgroups convertible into reactive functional groups including esters;trihalomethyl groups; alkoxy groups, alkyl groups when R is aromaticsaid alkyl and alkoxy groups preferably containing from about 1 to about12 carbon atoms: and the like. More preferably, for ease in preparationof the compounds and polymers thereof, G and G' are independentlyselected from hydroxyl groups and esters thereof, carboxylic orthiocarboxylic acid ester groups, carboxylic acid groups, acylchlorides, isocyanates, acetylenic groups, alkoxy groups, alkyl groupswhen R is aromatic, and primary or secondary amines. Most preferably,for ease in preparation of the compounds and polymers thereof, G and G'are the same and are selected from hydroxyl and esters thereof,carboxylic acid ester groups, carboxylic acid groups, acyl chlorides,isocyanates, acetylenic groups, and primary or secondary amines.

Preferred X and X' are independently generally as described for X inFormula I and preferred R and R' are independently: generally asdescribed for R in Formula I.

Such monomers are preferably prepared from monomers of the Formula:

    G.sub.n --R--X--CF═CF.sub.2                            Formula IV

wherein R and X are as defined for Formula 1; and G and n are as definedfor Formula IV.

Conveniently, the process for preparing such monomers comprises thesteps of:

(a) preparing a 2-halotetrafluoro compound of Formula V:

    Q--CF.sub.2 --CF.sub.2 --X--R--(--G").sub.n                Formula V

wherein X, R and n are as previously defined for X, X', R, R' and n inFormula IV: Q is bromine, chlorine or iodine; preferably bromine oriodine, most preferably bromine; and G" is a functional group G, aspreviously defined, or a functional group suitable for conversion into Gor G': and

(b) chemically modifying group G" to produce functional group G or G';

(c) dehalogenating the 2-halotetrafluoro compound to form thecorresponding trifluorovinyl compound

(d) thermally dimerizing the perfluorovinyl compound to form: aperfluorocyclobutane ring.

Step (b) optionally precedes or follows step (c) and/or (d), or steps(b) and (c) are simultaneous, generally depending on the relative easeof the reactions required and the relative sensitivity of the2-halotetrafluoro group or the trifluorovinyl group to the chemicalreactions required for step (b).

Monomers of Formula III are suitably reacted with di- or poly-functionalcompounds reactive with the groups represented by G and G' to formpolymers therewith by means within the skill in the art ofpolymerization. Preferably, the polymers are condensation polymers suchas polyesters, polyamides, polycarbonates, polyethers, epoxy resins andthe like.

In the practice of the invention, polymers having perfluorocyclobutanerings are found to adhere directly to materials such as compatiblepolymers, polymers having a common solvent, metals, particularlytextured metals, silicon or silicon dioxide, especially etched siliconor silicon oxides, glass, silicon nitride, aluminum nitride, alumina,gallium arsenide, quartz, ceramics, etc. Alternatively, an additionalmaterial or layer may be introduced between a layer havingperfluorocyclobutane groups and an adjacent layer to improve adherence;exemplary of such layers or materials are primers, adhesion promoterssuch as a silane, preferably an organo silane such astrimethoxyvinylsilane, triethoxyvinylsilane, hexamethyldisilazane[(CH₃)₃ --Si--NH--Si(CH₃)₃ ], or an aminosilane coupler such asY-aminopropyltriethoxy silane or a chelate compound such as aluminummonoethylacetoacetatediisopropylate [((isoC₃ H₇ O)₂ Al(OCOC₂ H₅CHCOCH₃)] are useful in the practice of the invention. A toluenesolution of the chelate is, for instance, spread on a substrate. Thesubstrate is then baked at 350° C. for 30 minutes in oxygen to form avery thin (e.g. about 5 nm) layer of aluminum oxide on the surface.Other means for depositing aluminum oxide are likewise suitable. Polymeris then deposited or otherwise applied. Other adhesion promoters aresuitably applied as layers on a substrate or on a layer of polymerhaving perfluorocyclobutane groups. Alternatively, the promoter isblended with the monomer before polymerization, negating the need forformation of an additional layer. The adhesion promoter may be blendede.g. at from about 0.05 weight percent to about 5 weight percent. Ingeneral less than about 0.05 weight percent is ineffective, and morethan about 5 weight percent adversely affects other desirable propertiesof the polymer, such as low dielectric constant or low water absorption.Additional adhesion promoters useful in the practice of the inventioninclude Chemloc speciality elastomer adhesives, fluoroepoxides includingfluorodiepoxide adhesives, vinyl tri-tert-butyl silane peroxide,neoalkoxytitanates, neoalkoxyzirconates, iminoxyl radical compounds,polyarylene sulfide resins, aromatic polyether-sulfone resins, aromaticpolyether ketone resins; alkoxy containing silicon compounds,organotitanates, organohydrogensilicon compounds, m-aminophenol(optionally in an adhesive blend such as a phenoplast blend), chromicacid, phosphoric acid, polyalkylsilicate containing finely divided metalsuch as zinc, chromium III complexes of such compounds as fumaric acids,epoxy resin with curing agents such as dianhydrides, ammonium; chromate,ammonium phosphate, chromium/chromium oxide mixtures,carboxyl-containing alpha-olefin polymers, fluorinated acids andalcohols, organic complexes of metals of groups 2B or 8 on the periodictable of the elements, porous layers of fluoropolymer particles,adhesive cements; optionally fluorinated rubber optionally withtackifiers such as urethane, epoxy or acrylic resins; hydrocarbonpolymer with halogenating agent, tri-allyl cyanurate, tri-allylisocyanurate, silicon tack agent, perfluoroalkoxy resin with resincontaining imide linkages, polysulfidic silane compounds, epoxyadhesive, alkali and/or alkaline earth alumino-borosilicate glass,bis-chloroalkyl vinyl phosphonate, polyurethane mastic, polyester filmbases, polyamide acid salt, metal oxides, fluorine resin promotersoptionally containing oxidants and/or inorganic acids,methylmethacrylate copolymers, zinc phosphate, zinc dispersion,water-hardening cements, peroxy organic compounds, fluorine resincontaining asbestos paper, lithium polysilicate, powdered acid andalkali-resistant inorganic substance (such as silica, graphite,molybdenum sulfate, or chromium oxide), aluminum borophosphate, alkylsilicates, alkali metal silicates, polyamine-imide primers,polyvinylcinnamic acid (optionally exposed to ultraviolet light),deposited carbon layers and the like. Alternatively, fillers includingsuperfine inert fillers, glass fillers, copper oxide and other metaloxides, colloidal silica, glass fibers, water hardening cements; mineralfibrils such as potassium titanate, titanium dioxide or boehmite;boehmite in other forms, asbestos and the like improve adhesion. Suchfillers are optionally coated or treated (e.g. with surfactant oradhesion promoter) to improve adherence to the polymer. Processesinvolving grafting such monomers; as acrylic esters and/or other vinylcompounds to the polymer (e.g. using catalysts or radiation), andoptionally treating the grafted molecules (e.g. saponification), also issuitable to increase adhesion to the polymer.

Adhesion is also coveniently enhanced by surface preparation,texturizing a substrate, for instance, by scratching, etching, plasmatreating, buffing and the like. Other means of surface preparationinclude degreasing, plasma treating, sonic cleaning, solvent treatment,SO₃ treatment (especially of silicon oxide), plasma glow discharge(PGD); PGD followed by adhesive monomers; air, oxygen, or ammoniaplasma; gas plasma etching; sodium treatment; wet chemical etching;electrochemical reduction; grafting; application and removal of metalssuch as aluminum; ion and electron beam techniques such as 6 MeVfluorine ions, electrons at intensities of about 50-2000 V, hydrogencations at about 0.2-500 ev to about 1 MeV, helium cations at about 200KeV to 1 MeV, fluorine or chlorine ions at about 0.5 MeV; neon at about280 KeV; oxygen enriched flame treatment; Accelerated Argon Iontreatment; low pressure plasma; irradiation in adhesive monomer vapor(radiation induced grafting); Fastblast Process; depositing carbonlayer(s); arc treatment; plasma polymerizing in the presence ofmaterials such as alkyl silanes or stannanes; sodium naphthalemide;roughening and/or oxidizing; treating with organic peroxide or polyamineoptionally followed by coating with silicone adhesives or adhesionpromoters; rough chromate coating; plasma depositing e.g. a hydrocarbonfilm; inert gas glow discharge (e.g. argon, helium, neon); lowtemperature plasma treatment; corona discharge treatment; microwavedischarge plasma; irradiating with high energy ions e.g. of at leastabout 0.1 meV/amu; abrasion optionally followed by a polymer such aspolyvinylcinnamic acid which is optionally cured, e.g. by ultravioletlight; reaction of metal oxide with aqueous aldehyde optionally withelectrical potential treatment; noble metal activator treatment;treatment with alkali metal (e.g. in organic solvent) and e.g.naphthalene, followed by contact with an oxidative mineral acid ormixture thereof; sand blasting; heat treating in solution of alkalimetal hydroxide; treatment with alkali metal or hydroxide thereof andhexamethylphosphotriamide and or aromatic hydrocarbon; and ozonetreatment.

In the cases where the polymer having perfluorocyclobutane groups isapplied as a coating, the other layer(s) are optionally referred to as asubstrate(s).

Polymers having perfluorocyclobutane groups, particularly those formedfrom monomers having at least three perfluorovinyl groups, havedensities approximating those of the monomer: therefore, when themonomer or prepolymer is applied to an object and polymerized thereonthere is insufficient dimensional change (shrinking or expansion) toresult in internal stress. Because of this property, the polymers areuseful as layers in situations where dimensional stability is important,such as a layer between other layers, e.g. an adhesive.

Polymers containing perfluorocyclobutane rings are suitably applied tothe other layer(s) by any means. Means for application are within theskill in the art. For instance, layers are suitably placed adjacent toone another, preferably they are contiguous or adhered in some mannersuch as by use of an inner layer between them. Layers of polymer havingperfluorocyclobutane groups are applied by methods such as vapordeposition (chemical or physical), sputtering, solution deposition,liquid-phase epitaxy, screen printing, melt spinning, dip coating, rollcoating, spinning, solution casting, brushing (e.g. varnish), spraycoating, powder coating, plasma deposition, dispersion spraying,solution casting, vacuum deposition, slurry spraying,dry-powder-spraying, fluidized bed techniques, radio frequency (RF)plasma deposition, welding, explosion methods including the WireExplosion Spraying Method and explosion bonding, press-bonding withheat; plasma polymerization; dispersion in a dispersion media withsubsequent removal of dispersion media; pressure bonding e.g. atsoftening point of polymer; adhesively joining a pair of surfaces one ofwhich contains a polymerization or crosslinking catalyst or initiatorsuch that polymerization is initiated on contact; heat bonding withpressure e.g. in a reduced pressure gaseous environment; vulcanization;extruding molten polymer onto a surface; hot-gas welding;baking-coating; sintering; placing one layer and the polymer layer(optionally in particulate form) between hot rollers; application in abinder which is optionally subsequently removed e.g. by pyrolysis, andthe like. Mono- and multilayer films are also deposited on a substrateusing a Langmuir-Blodgett technique, at an air-water or other interface.Spin coating, spray coating, solvent casting, screen printing andcasting from solvents are particularly useful. The polymer (monomer orprepolymer) is suitably applied to an object heated sufficiently hot toevaporate a solvent and/or polymerize the prepolymer or monomer or curethe polymer. For instance, an object such as a hot wire is suitablypassed through polymer, prepolymer, or monomer in a liquid state (e.g.molten or in solution), optionally as a spray or other comminuted form,at a rate calculated to result in deposition of a layer of predeterminedthickness. Alternatively, other materials such as metals includingaluminum, gold, copper, titanium, chromium, iron, tellurium, polymers,silicon, silicon dioxide, and the like are applied to polymers havingperfluorocylobutane groups by methods including those listed forapplications of the polymers, particularly by sputtering, vapordeposition and other means within the skill in the art for suchdepositions. Use of such techniques and other suitable coatingtechniques is within the skill in the art.

Any solvent for the monomer, prepolymer or polymer may suitably be used.Solvents include hydrocarbons such as o-, m- or p-xylene, mesitylenetoluene, benzene: chlorinated hydrocarbons such as chlorobenzene,dichloromethane; ketones such as methyl ethyl ketone, isopherone,acetone, methyl isobutyl ketone, and cyclohexanone; esters such asisoamyl acetate, n-butyl acetate, ethyl acetate, cellosolve acetate,methyl cellosolve acetate; ethers such as diglyme, tetrahydrofuran;amides such as N,N-dimethylformamide; and other polar solvents such asnitromethane, or 1-methyl-2-pyrrolidinone; and the like. The range ofsolvents facilitates smooth coatings in a variety of applications.

The polymer having perfluorocyclobutane groups optionally contains othermaterials (materials of composition different from that of the polymer,preferably non-polymeric materials) such as additives to change thechemical or physical properties of the polymer, for instancestabilizers, adhesion promoters and the like or, preferably,metal-containing compounds such as magnetic particles, such as bariumferrite (BaFe) iron oxide (e.g. Fe₂ O₃, optionally with Co), or othermetal containing particles for use in magnetic media, optical media, orother recording media; conductive particles such as metal or carbon foruse as conductive sealants, conductive adhesives, conductive coatings,electromagnetic interference (EMI)/radio frequency interference (RFI)shielding coating, static dissipation, electrical contacts and the like.In these respects the polymer can conveniently act as a binder resin.Certain materials may be residual in the layers from means for coatingthe polymers, for instance fillers, thickeners, surfactants and the likemay be used in screen printing, spray coating and the like.

Polymers having perfluorocyclobutane groups in their backbones,particularly such solid polymers, preferably those also having aromaticgroup and noncarbon atoms in their backbones are useful in compositeswherein the polymer surrounds, thus forms layers around such materialsas fiber glass, particularly fiber glass mats (woven or non-woven),graphite, particularly grapite mat (woven or non-woven), Kevlar™,Nomex™, glass spheres and the like. Such composites are especiallyuseful because of properties such as low viscosity, good wetting, andlack of volatile materials formed during polymerization. The polymersoffer properties such as toughness, thermal oxidative stability, lowdielectric, ignition resistance, flexural and tensile modulus, andenvironmental protection. Composites can be made from e.g. mats or otherlayers by means such as use of preforms, dipping mats in monomer orprepolymer, resin transfer molding (where the mat is placed into themold and monomer or prepolymer is added and heated to polymerize) andthe like. While the polymers are particularly useful as exterior layers,dielectric layers and the like, they are also useful as reinforcing orother interior layers such as reinforcements in tires, drive belts andthe like. Layers within composites are referred to herein as reinforcingor filling layers.

Polymer having perfluorocyclobutane groups are particularly useful as acoating for glass and other transparent materials because of thepolymer's clarity. Coatings for transparent materials are useful forscratch resistance, environmental protection including protection frommoisture and chemicals, flexibility, toughness, thermal stability andthe like. The coatings are useful on windows, green houses, skylights,oven windows, solar stills, and the like. Additionally, the polymer isuseful in anti-fouling coatings on such objects as boats; underwaterinsulation, particularly electrical insulation; and on vessels, helmets,valves (valve liners), molds, turbine blades and other parts, lightbulbs, carpet, tubs (e.g. for washers or driers), electrical switchenclosures, batteries, battery separators; film such as photographic andphotovoltaic film; bathtubs and shower coatings, tiles, swimming pool(liners), siding, roofing, UV filter, sleeping bags, sails, raincoats,and the like and in mildew resistant coatings. The flame resistance ofthe polymers renders them useful in ignition resistant paints and ascoatings on protective clothing, sick room equipment, medical and otherclothing, bed linens, instruments, mattresses, furniture, draperies,carpet, pillows, toys, tents, campers, fuel containers (liners),building materials, and the like. Because of the range of temperatureresistance of the polymers, they are suitably coated on cryogeniccontainers, autoclaves, ovens, and the like used in retortable pouches,cookware, utensils for coated cookware, heat exchangers and other heatedor cooled surfaces Microwave applications include roasting bags,microwave cookware and containers, popcorn bags, boiling bags, frozenfood trays, microwavable food containers and the like because ofresistance to degradation by heat or microwave radiation. Coatings ofthe polymer are additionally useful on food processing equipment,refrigerators (inside or outside) and the like.

Applied to layers such as film, electronic components, mirrors, glass,polymers of other composition, metals and alloys thereof, siliconoxides, silicon and the like, the polymer having perfluorocyclobutanegroups is useful in components including: non-glare or antireflectioncoatings (e.g. for photographic film) because of optical clarity andrefractive index: reflection coatings for metal or dielectric reflectorsbecause of properties of low dielectric, hydrolytic stability, clarity,or colorlessness; interference filters when applied to other polymersbecause of properties of optical clarity and low refractive index;polarizers; beam splitters; passive devices such as couplers because ofits index of refraction: photon detectors including photoconductive andphotoemissive detectors because of properties of optical clarity:photovoltaic devices such as solar cells because of properties ofhydrolytic stability, optical clarity: in imaging applications, e.g. inelectrophotography including Xerography and Electrofax because ofproperties of low dielectric and optical clarity: in thin film displays(e.g. electroluminescent and electrochromic) because of properties ofplanarization and low dielectric; in information storage devices becauseof properties of planarization, environmental stability; in thin filmactive components such as transistors and diodes because of propertiesof low dielectric; dopant diffusion layers in implant masks; in thinfilm integrated circuits as dielectric interlayers and the like becauseof low dielectric and ability to planarize; in microwave circuits suchas microwave integrated circuits (e.g. as microwave circuit boards)because of properties of low dielectric, low dissipation factor, and inother microwave applications such as telecommunications equipment,including receivers (e.g. antennas and probes) and transmitters(broadcasting and power), particularly as coatings for these, because ofresistance to degradation by microwaves, transmission of such waves andlack of absorption in the microwave range: in surface acoustic wavedevices such as transducers, delay lines, band-pass filters,pulse-compression filters, amplifiers, guiding components and otherapplications because of properties of low dielectric, refractive index,optical density; in charge-couple devices as scanners because ofproperties of planarization and optical clarity; in thermal detectors,thermal imaging devices, photothermal conversion devices because ofproperties of temperature stability; because of low dielectricproperties the polymer is useful as passivation layer in high speedelectrical switches; as a non-linear optical (NLO) polymer backbone toproduce active device structures for optical interconnects because ofproperties of low dielectric, high heat stability, and good opticaltransmission; fiber optic sensors.

Polymers having perfluorocyclobutane groups are useful in seals andgaskets, preferably used as a layer of a seal or gasket, e.g. around ascrim, but alternatively used alone. As a seal or gasket, the polymeroffers advantages such as chemical resistance, high thermal stability,oxidative stability, solvent resistance and the like.

Polymers having perfluorocyclobutane rings have properties of resistingtransport of chemical species that could attack an underlying layer,such as hydrolytic stability, hydrostatic stability, chemicalresistance, low moisture absorption, weatherability, and the like(hereinafter referred to collectively as environmentally protective,meaning protective from at least one substance or force to which anobject is exposed in its environment, including conditions ofmanufacture, storage and use) that result in utility as coatings toimpart surface passivation for instance to metals, semiconductors,capacitors, inductors, conductors, solar cells, glass and glass fibers,quartz and quartz fibers, polymers such as polycarbonate and the like toimprove corrosion resistance, reduce sensitivity to chemicals, protectfrom scratches. Because of optical clarity, the polymers are suitableenvironmentally protective and/or scratch resistant coatings even fordevices such as photovoltaics, optical disks, windows, eye glasses,mirrors (especially those used outdoors), optical fibers and the like.The polymers have properties of low coefficient of friction (forinstance, less than 0.25 static coefficient and less than 0.16 dynamiccoefficient of friction), scratch resistance, high heat resistance,chemical resistance, and colorlessness that result in utility ascoatings for tribological applications (interfacing surfaces in relativemotion) such as wear-resistant coatings and lubricating coatings. Theyare also useful in decorative applications such as clear coating forpreserving automobile finishes e.g. as an overcoat to paint, as anundercoat to smooth paint or in automotive body panels, buildingmaterials, wall papers or other wall coverings, siding, displaymaterials and the like; in fabrication of structural forms as coatingsfor flame resistance, weather resistance, moisture resistance and suchas on thermoplastics, wood, metal, fibers, and powders. Because of lowtemperature curing, low dielectric, low moisture absorbance, chemicalresistance and optical clarity, layer(s) of polymers havingperfluorocyclobutane groups or materials having such layers areparticularly useful in electronic packaging such as multichip modules,multi-layer chips, microwave circuits, planarization layers, opticalinterconnect lines, circuit boards, cable insulation and the like. Thepolymers are also useful as environmentally protective layers and impactabsorbing layers for micromachines.

Resistance of polymers having perfluorocyclobutane rings to radiation(e.g. electron-beam, gamma-waves and alpha particles) results in theirusefulness as layers in objects exposed to radiation, such asinstruments: or packaging to be sterilized by radiation, as substratesfor films, in electronics exposed to radiation and the like. Forinstance, the polymers are useful as passivation coatings on medicalinstruments and in packaging for medical devices such as bandages,operating equipment and the like. Similarly, the polymers are useful ine.g. X-ray films. Because the polymers are both radiation and heatresistant, as well as resistant to chemicals, including oxygen andmoisture, their usefulness extends to labware including petri dishes;incubator windows, window coatings and linings: oxygen tents and masks;sterilizable (gamma ray and/or autoclavable) equipment such as trays,surgical drapes, medical table surfaces, medical clothing; surgicalpacks; body fluid containers; and the like.

The chemical resistance of polymers having perfluorocyclobutanepolymers, particularly polymers having perfluorocyclobutane groups,aromatic groups and non-carbon atoms, preferably oxygen or sulfur in thebackbones thereof, renders such polymers useful for protection fromchemical attack. In addition to passivation, such use includes maskingof underlying layers for solder, for etching, for module fabricationgraphs device and the like. The polymers are useful as cable jackettingfor e.g. optical, electronic, and superconductive wires or fibers.

In electronics applications, varieties of substrates are coated withpolymeric materials either for selective etching or for passivation.Typical substrates include silicon, silicon oxides, gallium arsenide orother compounds of metals of Groups IIIA and IVA of the periodic tableas basic semiconducting materials for forming: transistors, diodes, andcapacitors: silicon dioxide, silicon nitride, or phosporus-doped silicondioxide as dielectric materials for interlayer insulation andpassivation: aluminum or polycrystalline silicon as conducting materialsfor e.g. contacts, interconnections, and electrodes; chromium or alloysthereof e.g. used in optical masks for photolithography; or copper asconducting material used e.g. in printed circuit boards. Silicon is amajor semiconducting material in microelectronic devices. Itadvantageously begins microfabrication in the shape of wafers. Thesurface of a silicon wafer or that of a epitaxially grown silicon layeris cleaned for polymer film deposition. A silicon surface is generallycoated with an oxide layer, e.g. by thermal oxidation or by chemicalvapor deposition, before being coated with a resist. Highly dopedpolycrystalline silicon is, however, generally coated with resist to bepatterned to form electrodes or interconnections in integrated circuits.Such a material (also called polysilicon) is deposited e.g. on an oxidelayer from the vapor phase by pyrolyzing silane. Polycrystalline siliconis useful e.g. to form electrodes in capacitors and transistors. To formelectrodes, before patterning, the layer is preferably doped e.g. bythermal diffusion or by ion inplantation to increase conductivity.

Typically, surface flatness of a silicon wafer used in a semiconductordevice does not deviate from optical flatness more than about 70 μm.Additional deviation is generally caused by oxide layer depositionbecause of a difference in thermal expansion coefficient between oxideand silicon. Polymers having perfluorocyclobutane groups are suitablyused to planarize the wafer, which allows the production of smallercircuitry (higher density). Such polymers can be applied and allowed toadhere during thermal cycling.

Gallium arsenide (GaAs) and its homologues are also frequently used insemiconductor devices such as high-speed transistors, high speedintegrated circuits, light-emitting diodes, and laser diodes, and thusis a useful substrate for layer(s) of polymer havingperfluorocyclobutane groups. Silicon dioxide, as a common insulator insemiconductor devices, is also a suitable substrate for polymer layersaccording to the practice of the invention. It is often formed onsilicon by thermal oxidation of the surface with oxygen or water vaporat a temperature between 1000° and 1200° C. or is, optionally,chemically deposited onto a substrate, not necessarily silicon, e.g.from the vapor phase, e.g. by the oxidation of silane with oxygen at atemperature between 400° and 500° C. Silicon dioxide is hydrophobic butreacts with water vapor in the atmosphere to form silanol (Si--OH), or asilanolated surface is formed in the chemical vapor deposition ofsilicon dioxide. Surface treatment to enhance adhesion is preferredbefore applying a polymer layer. Silicon nitride is convenientlydeposited vapor phase from e.g. silane and ammonia at a temperaturebetween 700° and 800° C. Silicon nitride is often a barrier forselective oxidation of silicon surface. Phosphorus-doped silicon dioxideis advantageously deposited vapor phase by the reaction of oxygen withsilane and phospine (PH3). It is useful for e.g. interlayer insulationand passivation of devices. A surface treatment is preferred prior topolymer film deposition. Chromium is a useful opaque layer in opticalmasks conveniently at a thickness of about 0.08 to 0.01 μm, e.g.deposited by vacuum evaporation or sputtering. Copper is widely used asa conductor in electric and electronic industries. In printed circuitboards, a copper foil is conveniently patterned lithographically to forminterconnections between electronic components. Polymers havingperfluorcyclobutane groups are advantageously deposited on any of thesesubstrates.

The surface onto which a polymer film is applied is preferably clean andfree from dust particles to avoid adhesion problems and/or defects inthe film. Cleaning of a silicon wafer surface may, for instance,involve: (1) boiling in a solvent, e.g. trichloroethylene, (2) washingin another solvent, e.g. acetone (room temperature), followed by (3)boiling in an acid, e.g. concentrated nitric acid. In a typical process,steps 1 and 2 take about 5 minutes each and step 3 takes about 15minutes. Other substrate treaments include, for instance, etchingsilicon dioxide, with aqueous hydrofluoric acid (HF); hexamethyldisilane (HMDS) treatment of polysilicon, silicon dioxide, phosporusdoped silicon dioxide or silicon nitride.

Practice of the invention is particularly useful as one or more layers,optionally with layers of different composition, on substrates such aswires, fibers (synthetic and natural), cables, and other elongatedobjects which can be coated on all exposed surfaces. The polymers areuseful as sleeving, cladding, flame resistant coatings and in additionto being applied by coating means already enumerated can be applied, forinstance as tape wound around the elongated object(s). High thermalstability with continuous service at about 200° C. or greater beingpossible, while maintaining excellent electrical and dielectricproperties combined with high resistance to chemicals and solvents, andlow coefficients of friction and surface energy of polymers havingperfluorocyclobutane groups result in utility, for instance, includingtape and wire insulations (particularly in high temperature, highfrequency applications) capacitor dielectrics, coaxial connectors, coilwrappers, transformers and as a glass fiber laminate for printed circuitboards. As a material having a low index of refraction as measured byrefractometer, in addition to its thermal, hydrolytic and chemicalstability, flame resistance, easy curability and compatibility withother materials such as other polymers, polymers havingperfluorocyclobutane groups are particularly useful in wave guides ascoatings (both claddings and buffering) for optical fibers or inmultichip modules or passive devices. Because of the low refractiveindex, hydrolytic stability and heat stability, the polymers aresuitable for use in multilayer optical films for band pass filters andinterference coatings.

Coatings can be applied, for instance, as colloidal aqueous dispersionsby such means as spraying, dipping, flowing or casting and to obtain a,preferably continuous and/or uniform, coating followed by an initialheating is used to remove solvents e.g. at about 100° to 200° C. andthen by curing at about 190° to about 300° C. The polymers can also beapplied by extrusion, electrostatic spraying and fluidised bedtechniques. A particularly preferred embodiment of the invention includelayers of polymers having perfluorocyclobutane groups over opticalfibers, e.g. glass fibers. Without an effective coating, the fibersdeteriorate from exposure to moisture, e.g. SiO₂ develops hydroxy groupsand there is a large resulting optical loss. Such a coating is typicallyapplied as a prepolymer solution, preferably of sufficient viscosity tospread evenly to form a uniform coating, from which the solvent isremoved (some curing optionally occurs) to form a, preferably tackless,coated fiber by rapid heating, e.g. in a plasma (UV, electron beam),infrared (IR) oven or the like this heating is optionally followed byadditional heating or other curing to achieve a polymer which ispreferably at least about 50 percent cured, more preferably at leastabout 80 percent cured, most preferably at least about 99 percent cured.The polymer is a suitable outer coating for such optical fibers becauseof the polymers' flame retardancy, flexibility, heat durability, lowmoisture uptake and hydrolytic stability. Such outer coatings areapplied by means within the skill in the art such as by extrusion.

For high-density integrated circuit applications, multipleinterconnections, which preferably consist of alternating metal anddielectric layers, are very important. Such interconnections enhanceefficiency of chip utilization and increase design flexibility.Multilevel structures now have feature sizes of 1 μm, and it isprojected that future feature sizes will reach the range of 0.5 μm.Metallization of dielectrics makes it possible to obtain highly packed,multilevel interconnectors. Polymers applied according to the practiceof the invention, e.g. by spin coating, planarize underlying topographyto provide a surface suitable for the next metal deposition. The degreeof planarization is determined by the ratio of the step height with thepolymer coating to the initial step height of the metal pattern withoutthe coating. For multilevel applications, vias for metal connectionshave to be formed to make contact between interconnection levels.Subtractive photolithography techniques in which a photoresist isapplied on top of a polymer coating are suitable. Then a cured polymerfilm is etched, e.g. using a photoresist as an etching mask. A middlelayer in a trilevel or multilayer resist system is often silicondioxide. The layer can be deposited e.g. by vacuum evaporation ordeposition, but is conveniently deposited by spin coating. Such acoating is called spin-on glass and is tetraethoxysilane dissolved inethanol, which when deposited and baked, results in a layer of silicondioxide.

Polymers having perfluorocyclobutane groups, particularly those havingperfluorocyclobutane groups in a polymer backbone, which also hasnon-carbon atoms and aromatic hydrocarbon groups, preferably separatingthe perfluorocyclobutane groups exhibit dielectric properties suitablefor electronic applications such as insulators in multichip packaging(multichip modules), multilayer electronic structures, capacitors, ringoscillators and the like.

Multichip packaging offers the potential for fabricating circuits withincreased density and higher performance at lower cost than is presentlyfeasible. Multichip packaging designs reduce the distance between thechips, thus reducing the necessary wire length. Many multichip circuitdesigns require multiple levels of interconnection due to the wiringdensity of the design. This wiring density can be achieved with currentthin film technology. The interlevel dielectric material determines themaximum density of the circuit through the line impedance and spacingnecessary to minimize crosstalk between signal lines. A material withlower dielectric constant allows closer packing of interconnect lines,and thus provides higher density. Higher density and shorterinterconnect lengths also permit the circuit to operate at higherspeeds. Conveniently, polymerization of monomers containingperfluorovinyl functional groups is a thermal process which does notrequire catalysis and does not generate any volatile by-products. Tocast the material as a thin film on a substrate, it is convenient toprepolymerize the monomer to an intermediate degree of conversion of thefunctional groups. The prepolymer can be handled either as a melt or insolution, and can be fully cured to the final thermoset after being castas a film. Prepolymerization, or B-staging, is performed by heating theneat monomers to a temperature between about 100° C. and about 190° C.for from about 1 min. to about 8 hours, depending upon the temperature.The extent of reaction can be determiend from the reduction of theresidual heat of reaction measured by differential scanning calorimetry(DSC).

Polymers having perfluorocyclobutane groups exhibit low water absorption(for instance about 0.025 weight percent water uptake bypoly1,1,1-tris(4-trifluoroethyloxyphenyl)ethane] and about 0.04 percentby weight water uptake by poly4,4'-bis(trifluorovinyloxy)biphenyl] asmeasured by ASTM D-570-81) and desorption of the water within about 24hours. Such low water absorption avoids the increase in dielectricconstants associated with water absorption and the resulting degradationof electrical characteristics of structures in which they are used as adielectric. The chemical resistance of such polymers is also excellent,such that thin films easily withstand typical metal etching processes.These films withstand hours at elevated temperatures in acid andalkaline baths with apparently little effect.

Thermogravimetric Analysis (TGA) measures the weight of a bulk sample asa function of temperature and time. At a 10° C. per minute ramp rate,the onset of weight loss is observed above about 350° C. in air andnitrogen.

Isothermal weight loss is a more representative indication of theability of any polymer to withstand processing at a given temperature.In both air and nitrogen environments at 350° C., after 1000 minutes inthese environments poly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane]loses less than about 1.2 weight percent, preferably less than about 1percent weight in nitrogen and about 6 percent by weight in air. Thepolymers exhibit stability at temperatures up to 400° C., as observed inannealing of aluminum.

In fabrication of microelectronic devices, relatively thin defect freefilms, generally 1 μm thick, are advantageously deposited on asupporting inorganic substrate e.g. silicon; or silicon-containingmaterials such as silicon dioxide, alumina, copper, silicon nitride;aluminum nitride; aluminum, quartz, gallium arsenide and the like. Inthe practice of the invention, coatings are conveniently prepared fromprepolymers reacted to a molecular weight, for instance, of about 1600Mn (number average), 4900 Mw (weight average), 11300 Mz (high average)preferably greater than about 5000 Mw. These prepolymers are completelymiscible with a variety of organic solvents such as xylene, mesitylene,n-butyl acetate and the like. The dissolved prepolymer can be cast ontoa substrate by common spin and spray coating techniques. The viscosityof these solutions is important in controlling coating thickness byeither deposition technique.

Films of polymers of perfluorovinyl-containing monomers are coated onsalt substrates by spray deposition and cured in air at about 250° C.for about 2 hours. This cure period is selected as corresponding to theminimum time for the elimination of the reaction exotherm as measured byDSC. After curing the films are removed by dissolving the substrate inwater bath. The resulting films are between 25 μm and 50 μm thick.Samples for dielectric spectroscopy are metallized films prepared bysputtering 100 nm of Au (gold) in an Ar (argon) plasma onto both sidesof the films. Disks 9.5 mm in diameter are punched out of the metallizedfilms. These disks are used to measure both the dielectric permittivitywith an HP 4192 Impedance Analyzer and the dissipation factor with aGenRad 1615-A Capacitance Bridge, both according to manufacturer'sdirections. Spectroscopy shows a dielectric constant of about 2.45 anddissipation factor of about 0.0005 forpoly[1,1,1-tris(4-perfluorovinyloxyphenyl)ethane].

Samples for dielectric breakdown measurements are not metallized, butare placed between a copper plate and a 6.4 mm steel ball as electrodes.The voltage source is a Bertan Model 205A-10R Power supply driven by aramp generator at 200 V/S (volts/second). Interpretation and meaning ofsuch dielectric measurements is within the skill in the art such asreflected in "Dielectric Materials and Applications" ed. by A. R. vonHippel, The MIT Press, Cambridge, MA, 1966.

To form a sample illustrative of multichip modules, silicon substrates(100 mm diameter) having 1 μm of thermal oxide are cleaned with anorganic solvent. Then they are metalized using 2 micron Al, Cu-1% whichis sputtered then patterned and etched using an aluminum etch solutionof (50 weight percent water, 42 weight percent phosphoric acid, 5 weightpercent acetic acid and 3 weight percent nitric acid) to form groundplane and bond pad areas. Under the given conditions, about 2 μm ofundercut occurs on each of the exposed sides of the Al wiring traces.

After removal of the photoresist, a coupling agent e.g.vinyltriethoxysilane is applied to the substrate surface and is followedby a prepolymer solution. The coupling agent preferably has an endattached to the SiO₂ and AlO₂ surfaces, and another attached to thepolymer. The prepolymer is spin coated under conditions which result inabout 5.5 pm final polymer thickness. The low viscosity, high solidscontent prepolymer solution affords a very high degree of planarization.The polymer is thermally cured to about 95%, such that remainingunreacted perfluorovinyl groups crosslink into the subsequent polymerlayer to enhance polymer-to-polymer adhesion.

Vias are etched into the polymer by sputter depositing a 0.3-0.5 μmcopper transfer mask over the surface. The copper mask is defined andetched using a bath solution of the following weight percent ofingredients 89, water; 8, nitric acid: and 3, acetic acid. After thephotoresist is stripped, the substrate is subjected to a barrel plasmaetcher (LFE 301C) using a 86% 02, 14% SF6 gas mixture.

The copper mask is subsequently removed by an acid bath 59 weightpercent water and 41 weight percent nitric acid. This acid bath mask hasless effect on the exposed Al via pads than the weaker bath used todefine the via cuts. Next an in-situ Ar back-sputter is used to deposita layer of metal and the process above is repeated. Each new polymerlayer is subjected to a full cure. The Si substrate is adhered to aalumina base with a low temperature cure epoxy. Wire bonds are madebetween the external Si substrate pads and the thick-film conductors onthe alumina package. Hermetically sealing is optional because of thehydrophobic nature of the polymer. The module package is placed on aninterface printed wiring board consisting of power supply, monitor,keyboard and external floppy drive interconnects.

The low dielectric, air curability, low moisture absorbance, thermalstability, and planarity of polymers having perfluorocyclobutane groupsmakes them particularly useful in such applications as dielectrics,especially in multichip modules; protective coatings; planarizinglayers; substrates and the like.

Layer(s) of polymers having perfluorocyclobutane groups are optionallypatterned such as for photoresists and by such means as wet etching,plasma etching, reactive ion etching (RIE), dry etching, photo laserablation, which are within the skill in the art as illustrated byPolymers for Electronic Applications, Lai, CRC Press (1989) pp. 42-47.Patterning can be accomplished by multilevel techniques in which thepattern is lithographically defined in a resist layer coated on thepolymeric dielectric layer and then etched into the bottom layer. Aparticularly useful technique involves masking the portions of polymer(or prepolymer) not to be removed, removing the unmasked portions ofpolymer, then curing remaining polymer, e.g. thermally. Methods withinthe skill in the art such as wet-etching or oxygen plasma techniquessuch as reactive-ion etching, other plasma etching, reactive ion etching(RIE) wherein substrates are placed between electrodes (usually plateelectrodes which sustain a radio frequency (RF) plasma), reactive ionbeam etching (RIBE), ion beam etching (IBE) in which a beam of reactiveions (e.g. 0+) are beamed onto the substrate, laser ablation and thelike are suitable for etching. The polymers can provide a flexible,X-ray transparent substrate for an X-ray absorbant like gold which ispatterned onto a polymer film, preferably on a substrate, e.g. a siliconwafer which is optionally removed, e.g. by etching.

Polymers having perfluorocyclobutane groups are particularly useful forforming planar layers, that is layers which are very smooth as indicatedby measurements of surface smoothness using a profilemeter commerciallyavailable form such companies as Tencor Instruments. A surface may bethought of as having peaks and valleys. A pen follows the surface up anddown as it goes across the surface measuring distances up and down.Average roughness (surface roughness) is the average of such distancesmeasured from the center line outward and is referred to as RA. Thebiggest peak to valley measurement made in a pass over a surface isreferred to as RT. Layers of perfluorocyclobutane containing polymers onsubstrates originally having a surface roughness of 100-150 Å (such asaluminum or polished nickel) preferably have a planarity after coatingof less than about 100 Å, more preferably less than about 50 Å.

To achieve such planarity, a coating is advantageously applied such thatthe polymer can flow to level roughness introduced in applying thepolymer or roughness in the substrate or in metals or ceramics processedonto the substrate. Thus, coatings for planarity are preferably appliedby means such as spin coating or spray coating in which the surfacetension can function to keep the surface of the coating flat. Othercoating means which allow planarity to result include spraying anddipping. These methods and spin coating are within the skill in the art,spin coating art being illustrated by such references as Jenekhe, S. A.,"Polymer Processing to Thin Films for Microelectronic Applications" inPolymers for High Technology, Bowden et al. ed., American ChemicalSociety 1987, pp. 261-269.

A solution, preferably of prepolymer, is spread onto the substrate whichis held on a vacuum spindle. The substrate is then accelerated up to aconstant rotating speed, which is advantageously held for a timesufficient to allow preceding to an even thickness, e.g. 30-60 sec. Thesolution film, thinned by centrifugal force, is dried to form a solidpolymer film. The film thickness decreases with increasing time, rapidlyapproaching a uniform film thickness.

After a polymer film is formed e.g. by a spin-coating process, the filmis conveniently baked. The baking evaporates solvent remaining in thefilm and generally polymerizes the monomer or prepolymer morecompletely. Baking temperatures are preferably from about 180° C. toabout 300° C., more preferably from about 250° C. to about 300° C.Polymers having perfluorocyclobutane groups advantageously havesufficient hardness to allow polishing of a coating to further improveplanarity.

Polymers having perfluorocyclobutane rings (preferably polymers havingsuch rings in the backbone along with linking groups, preferably oxygenor sulfur, and aromatic rings) are particularly useful in magnetic mediaor other information storage media, e.g. tapes or disks, especially harddisks. The planarization properties; thermal, water and chemicalstability: mechanical properties such as hardness, flexural and tensilemodulus, flexibility, toughness, elongation, and flexural strength; curetemperatures; lack of volatiles or other by-products produced inpolymerization or curing; and low coefficient of friction make thepolymers useful for any or all of several layers on hard disks. Harddisks are generally made up of a substrate, one or more undercoat layers(often nickel or nickel phosphorus), at least one magnetic coating(often an alloy of cobalt and a non-magnetic metal like chromium), andat least one overcoat (often carbon, e.g. sputtered or wet-coated). Thepolymers are useful as undercoat and planarization layer(s) on anysubstrate suitable for disks such as ceramic, glass, canacite(ceramitized glass), or metal such as aluminum, titanium, magnesium,nickel coated aluminum, nickel, plastic (e.g. polyetherimide), or thelike. Used as a planarizing coating, the polymer replaces metals such asnickel now used and ground or polished to the desired smoothness(generating waste nickel). A polymer planarization layer is optionallyadditionally smoothed as by polishing, e.g. with very fine grit padssuch as 8000 grit pads. A planarization layer is preferably from about20 to about 1000 Argstroms (Å) thick, more preferably from about 50 toabout 100 Å. The planarity offered by polymer layers according to thepractice of the invention is illustrated by the planarity of anunpolished spin coating ofpoly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane] on an aluminum diskwhich has a planarity of 40 Å as measured by a profilemeter. Thesubstrate is optionally treated as previously outlined to improveadhesion. The polymer advantageously lends mechanical strength withoutintroducing curvature or roughness so that thin substrates are moresuitably used. Independently, the polymers are also useful forintermediate layer(s), including magnetic layer(s), which may contain orhave adhered thereto, the media, e.g. particles or a layer, applied e.g.by sputtering, of iron oxide, optionally with cobalt (especially as adeposited layer), barium ferrite, a mixture or alloy of cobalt and e.g.chromium and/or tantalum, herein after referred to media containinglayer(s). Media containing layer(s) are suitably used on one or moreplanarization layers of polymer, metal (e.g. nickel) or other material.Alternatively, the media is used in or on the planarization layer toavoid a coating step. The media containing layer is optionally theoutermost layer or optionally has overcoat(s). Independently of its usein other layers, the polymer is suitably used in one or more overcoating layers which cover the media-containing layer(s) and providesmooth, protective, cushioning, planarizing and/or lubricatingcoating(s) to protect the media from environmental damage or damage fromthe reading and/or writing head of a disk assembly. Layers of polymeraccording to the practice of the invention are also useful as thesubstrate for the other layers. For use as a substrate, the polymerpreferably has a hardness of at least about 4 B as measured by ASTMD-3363.

Optical recording media including polycrystalline tellurium films showrapid degradation in high humidity or oxygen environments. Tellurium,for instance, is oxidized upon exposure to air, but under dry conditionsa stable passivating layer is rapidly formed preventing furtheroxidation. Water destabilises this thin oxide layer, and oxidation ofthe tellurium metal proceeds until it is all consumed. In the practiceof the invention, polymers are applied as a barrier or protecting layerto protect the thin layers of tellurium or other optical media fromenvironmental gases and moisture. In one embodiment an air sandwichstructure utilises a substrate on which the tellurium metal isdeposited; annular spacers then provide the supports for the top polymerfilm and leave a cavity immediately above the metal. The polymer isoptionally used to overcoat or encapsulate optical structures.

Because of their high dielectric strength, resistance to degradation byheat, oxygen and moisture and many chemicals polymers havingperfluorocyclobutane groups are particularly useful as capacitordielectric (films). To make a metallized film capacitor, for instance,the polymer has a layer of such metals as aluminum or zinc adhered toits surface e.g. by physical (preferably vacuum) deposition. Then thefilm is e.g. wound and, preferably, a clearing voltage is applied tocause localized breakdown discharges at any weak spots in the dielectricto stop the discharge by causing evaporation of metal around the faults.

Polymers having perfluorocyclobutane groups are also useful in displayssuch as flat panel displays, especially liquid crystal (LC) displays,because of their clarity, resistance to temperatures experienced infabrication, low temperature cure, hydrolytic and chemical stability. Acircuit for controlling the LC display is advantageously assembled, thena layer of the polymer is applied over the circuit by means analogous tothat now used for such polymers as polyimides. Another polymer, e.g. apolyimide, is optionally applied over the perfluorocyclobutanering-containing polymer, adjacent the liquid crystal material, or theliquid crystal material is used adjacent the perfluorocyclobutanering-containing polymer. A polymer used adjacent a liquid crystal ispreferably buffed or texturized to enhance alignment of liquid crystals.When the polymer having perfluorocyclobutane groups (as a first polymer)is used with another polymer (as a second polymer), the first polymer isadvantageously a protective layer to lend e.g. hydrolytic stability,planarization and good mechanical properties to the second polymer.Alternatively, whether or not a perfluorocyclobutane ring-containingpolymer is used between the controlling circuit and the liquid crystal,such polymers are useful as outer layers, adjacent the liquid crystaland/or on a different layer which is adjacent the liquid crystal. Anelectrode, electroconductive grid or other display controlling device isoptionally introduced into the polymer or between layers.

Because of their resistance to chemicals and moisture, polymers havingperfluorocyclobutane groups in the backbones thereof are suitable asintegrated circuit (IC) encapsulants. Encapsulants protect theelectronic devices from moisture, mobile ions, ultraviolet and visibleirradiation, α particles, and/or hostile environmental conditions. Anencapsulant preferably also enhances a fragile IC device, improves itsmechanical properties, and increases device reliability. Encapsulants ofthe invention advantageously have good electrical and mechanicalproperties; and are resistant to solvents, fluxes, and detergents.

High-density and/or high-speed integrated circuits (ICs) such as VLSIC(very large scale integrated circuit), VHSIC (very high speed integratedcircuits), and GaAs ICs require fine-line, multilayer conductor patternsto interconnect large numbers of input/outputs (I/Os) on highlyintegrated circuits. A package must provide effective removal of heatand environmental protection of the ICs. Layers of polymers havingperfluorocyclobutane rings assist in achieving these ends. For instancein high density printed wiring boards (PWBs) with plated Cu conductorand glass-reinforced polymer dielectrics: thick film multilayerinterconnects with screen-printed conductor pastes (e.g., Cu, Au) andceramic/glass dielectrics; multilayer co-fired ceramic with refractorymetals (W or Mo) and aluminia dielectric; wafer scale integration usingIC metallization processes on silicon substrates; and thin filmmultilayer (TFML) interconnections using Cu, Au, or Al conductors andpolymer dielectrics, specifically polymers having perfluorocylclobutanegroups. Substrates suitably include ceramics, metals, or silicon wafers.

Using polymers having perfluorocyclobutane rings in electronic devicesas described, particularly in integrated circuits, memory or datastorage means, in multichip modules or multi-layer chips, allows moreelectronic devices to be more compact than would be the case without thepolymers. Such compactness is particularly important in computers whichcan be smaller and/or lighter because of use of the polymers. Forinstance, the computers can have hard disk drives wherein data can bestored more compactly and/or using less weight because of the use of thepolymers.

The polymers are also useful for example as powder coatings in theelectronics industry for conformal coatings of electronic componentssuch as resistor networks, capacitors and hybrids. Powder coatings areapplied, for instance, by automatic fluidised beds, dipping equipment,and electrostatic spraying. For use as a powder coating, the polymerpreferably has a fusing temperature below about the melting point of tinlead solder more preferably below about 150° C., most preferably belowabout 130° C. Alternatively, monomers having a melting point below about200° C. preferably within the preferred fusion ranges are applied as apowder and heated to effect polymerization. Other components of adesired coating optionally admixed with the monomers beforepolymerization such that such components remain in the final polymerizedcoating. Powder coatings are suitably used as slot liners, forming anintegral coating over which windings can be directly laid. They are alsoused for the encapsulation of end windings of motors e.g. for use inportable drills and other motor-containing equipment. Electrostaticpowder coating offers an alternative to solvent-based enamels forinsulating magnet wires. Cured powder coatings impart properties such asimpact strenth, abrasion resistance, moisture resistance, temperaturecycling performance, electrical insulation characteristics and adhesionto a variety of substrate and device types, making them particularlyuseful in both the electrical and electronics industries.

Polymers having perfluorocyclobutane rings exhibit an unusual phenomenonwhich makes them particularly useful in a variety of applications andfacilitates unusual methods of achieving coatings. Theperfluorocyclobutane groups tend to segregate from hydrocarbon and polarportions of the molecules (analogous to the behavior of a surfactant).Thus, when coatings or layers are applied under conditions, such as heator solution, which allow the polymer to assume its equilibriumconformation, there are layers of fluoropolymer and layers of e.g.hydrocarbon in the case of a polymer having a hydrocarbon portion of themolecule. This segregating behavior has many advantages. For instance,the hydrocarbon portion of the molecule will intermix with or adhere toother substances present, e.g other polymers like polystyrene,polyolefins, polyurethanes, polycarbonates, epoxy resins, polyesters,polyamines, polyimides, and the like, particularly hydrocarbon polymerssuch as polyolefins and polystyrene. The perfluorocyclobutane portionsof the polymer, then, tend to align away from the hydrocarbon portionsof the molecule, leaving a fluorocarbon-like coating thereon. Similarly,when the non-fluorocarbon portions of the molecule are functionalized,e.g. with groups such as sulfonyl groups; acid groups includingcarboxylate groups; hydroxy groups; phosphonyl, phosphoryl, phosphine,or phosphate groups; silane groups such as vinyl or allyl silanes;siloxane groups; amine groups: sulfate, sulfonated, sulfoxide or sulfidegroups, such groups are attracted to similar substances or tosubstances, preferably substrates, with which they are otherwiseobserved to be compatible. For instance, a perfluorocyclobutanering-containing polymer having an aromatic portion having e.g. silane orsiloxane groups adheres to such substrates as silica or silicon waferssuch as are used in semiconductor applications and the like. Similarly,a perfluorocyclobutane ring-containing polymer having an aromaticportion having phosphonyl or phosphoryl groups adheres to suchsubstrates as calcium salts such as bone or ceramics and the like. Suchpolymers having sulfur-containing functionality such as sulfate,sulfonate, sulfoxide or sulfide groups adhere to iron andiron-containing alloys like steel. The fluorocarbon portions of themolecules are, thus exposed in each of the cases, exhibiting propertiesof toughness, low dielectric, low dissipation factor, lubricity, flameresistance, lower surface refractive index, lower surface tension, fluidbarrier properties, repellence of water, oils, soil and the like;resistance to heat, chemical resistance and other environmentalprotection. Protection from substances such as oil and water reducespenetration of these and improves dimensional stability of thesubstrate, rendering the substrate stain resistant. Migration ofsubstances such as plasticizers out of the substrate is reduced.Fluorocarbon character on the exterior of an object also impartsmold-release character. In addition, the coatings are scratch-resistant.

This phenomenon is useful, for instance, coating fibers, fabrics orother layers such as wool, cotton, and artificial fibers such aspolyesters, nylon, rayon and the like as well as forming layers onmolded and other shaped articles. Portions of polymers containingperfluorocyclobutane rings more like the fiber, fabric or layer tend toadhere to the layer while the perfluorocyclobutane portions of themolecule tend to align outside the fiber, fabric or layer. Suchproperties as flame retardancy, water repellency and the like areobserved in the coated fabric, fiber or layer.

One unusual consequence of the segregating phenomenon is that blends ofthe polymers having perfluorocyclobutane groups and other polymersresult in layered materials. It is observed, for instance, that a blendof polymers having perfluorocyclobutane groups and e.g. polystyrene whenshaped under conditions allowing segregation of molecular speciesappears to result in a layered material having hydrocarbon portions ofthe perfluorocyclobutane-containing polymer blended with the polystyrenewhile the perfluorocyclobutane groups form an outside layer. Because ofthis, e.g. 2 weight percent of poly[4,4'-bis(trifluorovinyloxy)biphenyl] in polystyrene results inresistance to the flame of a cigarette lighter for a period of 15seconds in ambient air. For instance, fibers or microfibers of blends ofthe perfluorocyclobutane ring-containing polymers and another polymer,e.g. polystyrene are conveniently formed, e.g. by extrusion. The fibersmay be prepared in a continuous or discontinuous manner and optionallyinto e.g. a non-woven mat which is optionally further fabricated such asby compaction, stretching, calendering, embossing, twisting, windingetc. to further alter or collect the resulting mat. Whenperfluorocyclobutane ring containing polymers are blended with otherpolymers it is preferable to select polymers of similar Tg (glasstransition temperature) such that both polymers are melted andsegregation is facilitated.

While polymers having perfluorocyclobutane groups are generally usefulas layers or coatings, the preferred polymers are generally those havinglinking structures and aromatic portions of the molecule. Morepreferably the polymers are formed by thermal polymerization of monomersof Formula I, most preferably where X is oxygen or sulfur, preferablyoxygen and R is an aromatic group. Among such polymers, boththermoplastic polymers such as polymers of bifunctional monomers such as4,4'-bis(trifluorovinyloxy)biphenyl; 1,3-bis(trifluorovinyloxy) benzene;9,9-bis(trifluorovinyloxyphenyl) fluorene; and1,1-bis(4-trifluorovinyloxyphenyl)-1-phenyl ethane;4,4'-bis(trifluorovinyloxyphenyl) sulfide;4,4'-bis(trifluorovinyloxyphenyl)isopropane;2,6-bis(trifluorovinyoxy)naphthalene; or2,7-bis(trifluorovinyloxy)naphthalene, preferably those which arecrosslinked by additional heat such as polymers of4,4'-bis(trifluorovinyloxy)biphenyl or9,9-bis(trifluorovinyloxyphenyl)fluorene and thermoset polymers such asthose containing trifunctional monomers, preferably more than about 0.5percent by weight trifunctional monomers are particularly useful. Thethermoplastic monomers are particularly useful in applications such asmolded circuit boards, film for tape automated bonding, ignitionresistant and water repellent coatings, where properties such asextrudability, melt processibility, tear strength, flame resistance,environmental protectiveness and the like are useful. The polymers whichcan be crosslinked by additional heat are particularly useful inapplications such as films and infrared coatings where properties suchas chemical resistance, thermosetting, solvent resistance and the likeare useful. The thermoset polymers are particularly useful inapplications such as planarization coatings, passivation coatings, andscratch resistance where properties such as solution processibility,hardness, thermosetting, low moisture uptake, low dielectric,passivation and the like are useful. Blends of the thermoset andthermoplastic polymers as illustrated by blends of polymers of1,1,1-tris(4-trifluorovinyloxyphenyl)ethane;1,3,5-(2-(4-trifluorovinyloxyphenyl)-2-propyl)benzene and mixturesthereof with polymers of 4,4'-bis(trifluorovinyloxy)biphenyl;9,9-bis(4-trifluorovinyloxyphenyl) fluorene;1,3-bis(trifluorovinyloxy)benzene; 2,7-bis(trifluorovinyloxy)naphthalene or mixtures thereof are useful when the high temperaturephysical (mechanical) properties, chemical resistance of the thermosetpolymer is needed but the thermoplastic imparts adhesion, loweredflexural modulus (toughness), flexibility, preferably without loss ofsuperior thermal oxidative stability or dielectric properties.

Some of the properties of perfluorocyclobutanecontaining polymers whichrender them useful as layers and coatings are listed below for arepresentative thermoplastic poly4,4'-bis(trifluorovinyloxy)biphenyl], arepresentative thermoplastic poly[4,4'-bis(trifluorovinyloxy)biphenyl]backbone crosslinked at 280° C. for 1 hour and a representativethermoset polymer (poly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane)

    __________________________________________________________________________                                                         THERMOSET                                                          THERMOPLASTIC                                                                            (WEIGHT                  PROPERTY    UNITS                                                                              TEST METHOD   THERMOPLASTIC                                                                            CROSSLINKED                                                                              PERCENT                  __________________________________________________________________________                                                         PURE)                    tensile strength                                                                          psi  ASTM D-882-83   5,500*     7,200*     9,6000*                tensile modulus                                                                           psi  ASTM D-882-83 200,000    255,000    253,000                  percent elongation                                                                             ASTM D-882-83    12          4      4.1                      flexural strength                                                                         psi                 10,800*     8,700*                            flexural modulus                                                                          psi  D-790-86      234,000    315,000                             coefficient of linear                                                                     ppm/°C.                                                                     Thermomechanical Analysis                                                                   85;71         30         90                    thermal expansion                                                                              E-831-86                                                     (CLTE)                                                                        Tg          °C.                                                                         Dynamic Mechanical                                                                             170                 286 (97%)                                Analysis D-4065-82/                 >300 (99%)                                Thermomechanical Analysis                                                     E-831-86                                                     stability in nitrogen at                                                                  minutes-                                                                           Isothermal Thermo                    500 min -17% loss       400° C.                                                                            loss in                                                                            gravimetric Analysis                                                     percent                                                                       by                                                                            weight                                                            stability in nitrogen at                                                                  minutes-                                                                           Isothermal                          1000 min -1% loss        350° C.                                                                            loss in                                                                            Thermogravimetric Analysis                                               percent                                                                       by                                                                            weight                                                            stability in air at 350° C.                                                        minutes-                                                                           Isothermal                          1000 min -1% loss                    loss in                                                                            Thermogravimetric Analysis                                               percent                                                                       by                                                                            weight                                                            Refractive Index (ηd) at                                                                   Refractometer by                                                                             1.510                 1.495                   1000 nanometers (nm)                                                                           manufacturer's directions                                    pencil hardness  D-3363-74                           HB                       durometer hardness                                                                             D-2240-86                           D-83 (85%)               Barcol hardness  D-2583-87                           B-34 (85%)               static coefficient of                                                                          D-1894-87                           0.25                     friction                                                                      dynamic coefficient of                                                                         D-1894-87                           0.16                     friction                                                                      weight percent water                                                                      percent                                                                            D-570-81      0.04                   0.025                   take up in 24 hour soak                                                       weight percent water                                                                      percent                                                                            D-570-81      0.22                   .14                     take up in boil-infinity                                                                       modified boil                                                                 unitl no                                                                      further gain                                                                  in weight                                                    dielectric at 10 khz                                                                           ASTM D-       2.41       2.59       2.45                     (kilohertz)      1510-87                                                      dissipation at 10 khz                                                                          ASTM           0.0003    0.0006      0.0005                                   D-150-87                                                     flammability     UL 94         V0         V0         V0                                        (Underwriters                                                                 Laboratory)                                                  flammability, LOI                                                                         percent                                                                            D-2863-87     42                                                         oxygen                                                            __________________________________________________________________________     *Sample impure                                                           

In no instance is the use of a term like fire retardant, fireretardancy, flame resistance or the like to be interpreted as implyingthose qualities in any actual fire condition, rather the terms indicatethat at least some of the polymers perform relatively better thancontrols in standardized tests. Numerical flame ratings are not intendedto reflect the hazards presented by these or other materials underactual fire conditions.

The following examples are offered to illustrate but not to limit thepresent invention. In each case, percentages are weight percent unlessotherwise indicated. Examples (Ex.) of the present invention areindicated numerically, while comparative samples (C.S.) are not examplesof the present invention and are indicated with letters.

Dielectric constant and dissipation factor measurements are conductedaccording to the procedures of ASTM D150-87. Tensile strength andmodulus and percent elongation are measured on an Instron model 1125according to the procedures of ASTM D-882-83.

Samples of [1,1,1-tris(4-trifluoroethenyloxyphenyl)-ethane] (TVE) and of4,4'-bis(trifluorovinyloxy) biphenyl prepared as taught in U.S.application Ser. No.07/534,818, filed Jun. 7, 1990 which is incorporatedby reference herein are used for the following Examples:

EXAMPLES 1-9 Investigation of the effect of solvents andprepolymerization on the attributes of coatings of poly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane]

Various degrees of prepolymerization are achieved using a B-stagingapparatus having an outer cylindrical insulated jacket with heat supply,open at one end to receive a vertical tubular reactor and a fluidizedbed of aluminum oxide between inner walls of the B-staging apparatus andthe tubular reactor. The apparatus is a Tecam model SBL-1 Fluidized SandBath commercially available from Techne, Incorporated. A thermocouple isinserted in the fluidized bed to monitor temperature. The tubularreactor is immersed into the fluidized bed to a depth of about 3/4 ofits height, such that the fluidized bed is approximately 6 inches (15.2cm) above the top of the TVE. The tubular reactor is equipped with amechanical stirrer, a vacuum inlet and a nitrogen inlet each withvalves. The vacuum inlet is used to remove the oxygen from the TVEmonomer before the reactor is immersed into the fluidized bed. Thenitrogen inlet allows nitrogen to enter the reactor to purge the reactorduring the deoxygenation procedure and to maintain an inert atmosphereduring the reaction. Before the reactor is immersed into the fluidizedbed, the polymer is deoxygenated. Oxygen is removed from the TVE monomerby subjecting the monomer for 2 hours at room temperature (22° C.) underhigh vacuum and then for an additional hour at 40° C. under high vacuum.After that time, the reactor is purged twice with nitrogen for a periodof 15 minutes each (this means that the vacuum valve is closed and thenthe nitrogen valve is opened to allow nitrogen to enter the reactor). Anitrogen atmosphere is maintained for 15 minutes before the nitrogenvalve is closed and the vacuum valve is opened again. This is done twotimes to give two 15 minute nitrogen purgings.

In each polymerization, a sample of the weight of the TVE indicated inTable 1 is placed in the tubular reactor and immersed in the fluidizedbed which has been preheated to the temperature indicated in the table.The reactor is maintained at the indicated temperature for the timeshown in the same: table. In each instance, a glassy solid polymer isobtained.

A Du Pont Instruments model 910 Differential Scanning Calorimeter (DSC)commercially available from DuPont Instruments, Inc. is used todetermine reactive groups (relative to TVE monomer) remaining after eachprepolymerization reaction. Each prepolymer contains a certainpercentage of reactive vinyl groups. The method for obtaining the totalenergy released and the percentage of reactive groups remaining is asfollows: A sample of each prepolymer is placed on a heating element ofthe DSC instrument and slowly heated from 20° C. to 400° C. at 10°C./min. During the heating process, the reactive vinyl groups react andrelease energy in the process. A DSC program is used to calculate thetotal energy released (shown in Table 1) after all of the remainingreactive vinyl groups in the prepolymer sample have completely reactedon the heating element. The percentage of reactive vinyl groupsremaining is calculated according to the formula: ##EQU1##

                  TABLE 1                                                         ______________________________________                                        The sample calculation above is for Sample No. 1 from Table 1.                                            Conditions                                                                            The TVE                                                               for Total                                                                             Percent                                   Sample or                                                                             Amount   Various    Energy.sup.a                                                                          Remaining                                 Example (g)      B-Staging  Released                                                                              Reactive                                  Number  of TVE   Conditions (Joul/g)                                                                              Groups (%)                                ______________________________________                                        A       all      Monomer,   432.05  00.00                                                      unheated                                                     1       30       140° C., 3 hrs                                                                    265.40  61.43                                     2       30       150° C., 1 hrs                                                                    321.10  74.32                                     3       30       150° C., 2 hrs                                                                    277.00  64.11                                     4       30       150° C., 3 hrs,                                                                   246.10  56.96                                                      R-1.sup.b                                                    5       80       150° C., 3 hrs,                                                                   220.25  50.98                                                      R-2.sup.b                                                    6       80       150° C., 3 hrs,                                                                   223.30  51.68                                                      R-3.sup.b                                                    7       80       150° C., 3 hrs,                                                                   224.30  51.92                                                      R-4.sup.b                                                    8       80       150° C., 3 hrs,                                                                   230.50  53.35                                                      R-5.sup.b                                                    9       30       160° C., 30                                                                       325.65  75.34                                                      min                                                          ______________________________________                                         .sup.a Each value is an average of two DSC runs wherein all available         perfluorovinyl groups are reacted.                                            .sup.b Run number                                                        

Yellowing of the prepolymer is observed when the oxygen is notcompletely removed from the TVE monomer, but the yellowing does notappear to affect coating quality. The prepolymer is colorless whendeoxygenation is complete.

Molecular weight distributions for the indicated prepolymers aredetermined using a Waters model M-6000 Size Exclusion Chromatograph(commercially available from Waters, Inc.) according to manufacturer'sdirections. Results are shown in Tables 2 and 3.

Mn is the number average molecular weight. Mw is the weight averagemolecular weight. Mz is the high average molecular weight.

                  TABLE 2                                                         ______________________________________                                        Molecular Weight Distribution.sup.a For B-Staged TVE                                B-Staged                                                                Ex.   Conditions  Mn      Mw    Mz     Mw/Mn                                  ______________________________________                                        1     140° C., 3 hrs                                                                     1200    2500   4800  2.11                                   2     150° C., 1 hrs                                                                      880    1400   2400  1.62                                   3     150° C., 2 hrs                                                                     1300    2900   6000  2.30                                   4     150° C., 3 hrs,                                                                    1600    4900  11300  3.00                                         R-1                                                                     5     150° C., 3 hrs,                                                                    2100    9800  29600  4.73                                         R-2                                                                     6     150° C., 3 hrs,                                                                    2000    8400  23700  4.18                                         R-3                                                                     7     150° C., 3 hrs,                                                                    2000    9300  27500  4.53                                         R-4                                                                     8     150° C., 3 hrs,                                                                    1900    6900  18200  3.65                                         R-5                                                                     9     160° C., 30 min                                                                     900    1500   2600  1.67                                   ______________________________________                                         .sup.a as obtained by Size Exclusion Chromatography                      

                  TABLE 3                                                         ______________________________________                                        Weight Percent of Each Oligomer.sup.a                                         Present in B-Staged TVE                                                                                              High                                                                          Molecular                                   B-Staged    Monomer   Dimer Trimer                                                                              weight                                 Ex.  Conditions  (%)       (%)   (%)   (%)                                    ______________________________________                                        1    140° C., 3 hrs                                                                     25.8      20.3  14.7  39.3                                   2    150° C., 1 hrs                                                                     40.8      27.5  15.6  16.1                                   3    150° C., 2 hrs                                                                     23.3      19.7  15.1  41.8                                   4    150° C., 3 hrs,                                                                    16.9      15.2  12.5  55.4                                        R-1                                                                      5    150° C., 3 hrs,                                                                     13.64     11.79                                                                               9.57 Na                                          R-2                                                                      6    150° C., 3 hrs,                                                                     14.20     12.51                                                                               10.03                                                                              Na                                          R-3                                                                      7    150° C., 3 hrs,                                                                     14.03     12.17                                                                               9.87 Na                                          R-4                                                                      8    150° C., 3 hrs,                                                                     15.36     13.77                                                                               11.09                                                                              Na                                          R-5                                                                      9    160° C., 30 min                                                                    39.1      27.2  15.8  17.9                                   ______________________________________                                         .sup.a as obtained by Size Exclusion Chromatography                           Na. = not measured                                                       

To test the prepolymers in coatings, clean solutions of the indicatedpreppolymerized polymers are made in the indicated solvents at weightratios of polymer to solvent of 70/30 percent, 60/40 percent and 50/50percent. Diglyme, mesitylene, o-xylene and n-butyl acetate are selectedfor investigation because they represent a wide range of types ofsolvents, having different points, viscosities and polarities, aresolvents for both the monomer and polymer and are known to be useful incoating processes. Each solution is tested using a Solitec model 5110(horizontal) Spin Coater, commerically available from Solitec, Inc. Foreach coating, a silicon oxide wafer substrate is centered onto a flatchuck, which is connected to a rotating spindle during spin coating, and0.25 ml of a solution of triethoxysilyl-benzocyclobutene (TES-BCR) inthe test solvent adhesion promoter is dropped onto the surface of thesubstrate from a syringe equipped with a 1 micron Gelman Acrodisc filter(commercially available from Gelman Science Company). The filter housingis made of polypropylene, and the filter is made ofpolytetrafluoroethylene and is 25 mm in diameter having inlet and outletconnections on the filter housing. The adhesion promoter is spread overthe wafer at a spin speed indicated in the Tables. A sample of 12 mLpolymer solution is applied over the surface of the substrate using oneof two methods:

For the examples in Tables 4 and Examples 6 and 7, the polymer isapplied onto the surface of the wafer using a 10 mL syringe equippedwith a filter (Method 1). For Examples 5 and 8, the polymer solution isprefiltered through a filter into a 100 g clean bottle; then the polymersolution is poured from the bottle over the surface of the silicon oxidesubstrate until the polymer solution covers approximately 3/4 of theentire surface of the substrate. (Method 2) For all examples: forpolymer coatings of 1.0 micron or less, a 0.20 micron filter is used:for polymer coatings thicker than 1 micron but less than 5 microns, a1.0 microfilter is used; for polymer coatings thicker than 5 microns, a5 micron filter is used. The filters are used to remove particles, whichwould degrade the coating quality.

Then the spin coater is turned on which causes the substrate to go intoa spread mode followed a spin mode. The polymer is spread over thesurface of the substrate at a spread speed, spread time, spin speed, andspin time as indicated in the Tables to give a uniform spin coatedpolymer solution.

Each coating is applied to a silicon wafer (substrate) 2 inches (5.08cm)in diameter. The silicon oxide substrates are commercially availablefrom Unisil Corporation, where the substrates are preheated and siliconoxide is deposited on the surface of the substrate. Each wafer iscleaned before spin coating using a LFE Plasma Systems model 301C BarrelEtcher (commercially available from, LFE Plasma Systems, A Mark IVCompany) according to manufacturer's directions. The Spin Coater is runaccording to manufacturer's directions under the conditions indicated inthe tables. After being coated, each wafer is removed from the spincoater and placed in a Blue M model B-2730 Curing Oven (commerciallyavailable from Blue M, a Division of General Signal) having aprogrammable temperature control, and being fitted with a filterednitrogen inlet and outlet such that a nitrogen atmosphere is maintainedduring curing with a flow of about 100 standard cubic feet per hour (2.8cubic meters/hour). The nitrogen is filtered using an HEPA 1 micronfilter. The prepolymer is further cured at 50° C. for 5 minutes, thenthe temperature is raised to 100° C. over a period of 15 minutes andmaintained at 100° C. for an additional 15 minutes, after which, thetemperature is raised to 150° C. over a period of 15 minutes andmaintained for a period of 60 minutes, after which the temperature israised to 250° C. over a period of 60 minutes and maintained for aperiod of 1 minute, after which the oven temperature is lowered to 20°C. and maintained until the coated wafer cools to that temperature.

After the curing, the film thickness is measured using a Nanospec/AFTModel 210 ellipsometer commercially available from Nanometrics, Inc. anda Tencor Instruments model Alpha-Step 200 profilemeter commerciallyavailable from Tencor Instruments, Inc.

Tables 4-5 indicate the results of the coating processes.

                  TABLE 4                                                         ______________________________________                                        Film Thicknesses (μm) of Different                                         B-staged Runs from a 50/50% Solid solution                                    in Four Different Solvents at Various Spin Speeds                                     Spin     140° C.                                                                         150° C.                                                                       150° C.                                                                       150° C.                                Speed    3 hr     1 hr   2 hr   3 hr R-1                              Solvent (rpm)    (Ex. 1)  (Ex. 2)                                                                              (Ex. 3)                                                                              (Ex. 4)                               ______________________________________                                        Diglyme 5000     0.9430   0.5906 1.0365 1.2080                                        1500     1.5586   1.1025 1.8296 Na                                    Mesitylene                                                                            5000     1.0636   0.6728 1.1272 1.4340                                        1500     1.8494   1.2148 2.1330 Na                                    o-Xylene                                                                              5000     1.3412   0.9863 1.5535 1.9180                                        1500     2.4900   1.8301 2.9712 Na                                    n-Butyl 5000     1.4511   1.0962 1.7187 1.972                                 Acetate 1500     2.6505   1.9413 3.3026 Na                                    ______________________________________                                         For each spin coating, the spin time is 30 seconds and the spread speed       and spread time are 500 rpm and 3.0 seconds, respectively. Film               Thicknesses are measured with the Nanospec/AFT. Na = Not available            Method 1 is used for spin coating the prepolymer onto the substrate           1micron fillers are used for each experiment.                            

                  TABLE 5                                                         ______________________________________                                        Film Thicknesses (μm) of Different B-staged Runs                           from Different Percent Solid solutions in                                     Four Different Solvents at Various Spin Speeds                                                 150° C.                                                                         150° C.                                                                       150° C.                                                                       150° C.                                         3 hr     3 hr   3 hr   3 hr                                          Spin     70/30    50/50  50/50  60/40                                         Speed    R-2      R-2    R-3    R-4                                   Solvent (rpm)    (Ex. 5)  (Ex. 6)                                                                              (Ex. 7)                                                                              (Ex. 8)                               ______________________________________                                        Diglyme 9000      5.75    1.2276 Na      2.3342                                       5000      7.70    1.5877 Na      3.1834                                       1500     22.22    3.0438 Na     6.82                                  Mesitylene                                                                            9000      7.32    1.4573 1.3193 3.20                                          5000     10.30    1.9121 1.7732 4.25                                          1500     24.53    3.5342 3.2864 8.31                                  o-Xylene                                                                              9000      7.75    1.8872 Na     3.95                                          5000     10.71    2.4954 Na     5.27                                          1500     22.22    4.5146 Na     9.98                                  n-Butyl 9000      7.71    1.9907 Na     4.08                                  Acetate 5000     10.73    2.5625 Na     5.38                                          1500     20.42    4.1041 Na     10.20                                 ______________________________________                                         For each spin coating, the spin time is 30 seconds and the spread speed       and spread time are 500 rpm and 3.0 seconds, respectively. Na = Not           available                                                                     For experiments 6 and 7, spin coating Method 1 is used.                       For experiments 5 and 8, spin coating Method 2 is used.                       A 5 micron filter is used for experiment 5 while a 1 micron filler is use     for experiments 6-8.                                                     

                  TABLE 6                                                         ______________________________________                                        Film Thicknesses (μm) of Different B-staged Runs                           from Different Percent Solid solutions in Four                                Different Solvents at Various Spin Speeds                                                       150° C.                                                                          150° C.                                                                        150° C.                                              3 hr      3 hr    3 hr                                              Spin Speed                                                                              50/50 R-4 40/60 R-4                                                                             50/50 R-5                                 Solvent (rpm)     (Ex. 9)   (Ex. 10)                                                                              (Ex. 11)                                  ______________________________________                                        Diglyme 9000      1.2529    0.6526  Na                                                5000      1.5654    0.8701  1.3791                                            1500      3.0003    1.5175  Na                                        Mesitylene                                                                            9000      1.3877    0.8751  Na                                                5000      1.8712    1.1225  1.6195                                            1500      3.5043    2.0482  Na                                        o-Xylene                                                                              9000      1.8473    1.0619  Na                                                5000      2.4501    1.2748  2.1485                                            1500      4.77      2.3979  Na                                        n-Butyl 9000      2.0166    1.1234  Na                                        Acetate 5000      2.6075    1.4257  2.3616                                            1500      4.99      2.6439  Na                                        ______________________________________                                         For each spin coating, the spin time is 30 seconds and the spread speed       and spread time are 500 rpm and 3.0 seconds, respectively. Na = Not           available                                                                

                  TABLE 7                                                         ______________________________________                                        Film Thickness (μm) For B-staged Run #5 From                               a 50/50% Solid Solution in Four Different Solvents                            at Various Spread Times                                                                         Film Thickness (μm)                                      Solvent Used                                                                             3 sec.       45 sec. 90 sec.                                       ______________________________________                                        Mesitylene 1.6195       2.8043  5.63                                          O-Xylene   2.1485       7.15    7.61                                          Diglyme    1.3816       1.8746   3.3102                                       N-Butyl    2.3616       8.39    8.34                                          Acetate                                                                       ______________________________________                                         For each spin coating, the spread speed is 500 rpm and the spin speed and     spin time are 5000 rpm and 30 seconds, respectively.                     

Data in Tables 4-7 show that the degree of B-staging of polymers of TVEis an important variable affecting the film thickness and coatingquality. Coating quality is determined from observed uniformity,including absence of holes; a standard deviation of less than about 0.1among 5 thickness measurements on different portions of a disk isconsidered good quality. There are also few color patterns of the typeproduced by thickness variations and no visible bumpiness. At a givenreaction temperature of 150° C., when the B-staged prepolymer isdissolved in a given solvent at a given concentration, the prepolymerthat has reacted longer gives thicker coatings. These results directlycorrelate with the results from size exclusion chromatography which showa progressive increase in the concentration of high molecular weightoligomers as the B-staging reaction time for forming the prepolymerincreases. The converse is true for the percentage of TVE monomerremaining after each prepolymerization reaction. Furthermore, it isbelieved that thicker coatings are observed because the viscosity of theprepolymer solution is directly proportional to the percentage of highmolecular weight oligomers in the prepolymer. There is also acorrelation of B-staging condition with observed coating quality. Thebetter quality coatings are achieved from prepolymers which arepolymerized at the longer reaction times (3 hrs at 150° C.). Prepolymersthat polymerize at 10° C. higher or lower than 150° C., regardless ofthe reaction time, generally give lower quality coatings. The prepolymercontaining 50.98% unreacted trifluorovinyether groups (Ex. 5) isobserved to give the best quality coatings for film thicknesses between1 and 4 microns.

Two other important variables affecting the film thickness and coatingquality are the choice of solvent and prepolymer concentration. Theorder in which film thickness is observed to increase with solvent is:n-butyl acetate greater than o-xylene greater than mesitylene greaterthan diglyme. This order is directly proportional to the boiling pointof the solvent. Prepolymer solutions of n-butyl acetate and o-xylene arebelieved to give thicker coatings because the solvent evaporates fromthe substrate more quickly. As the solvent evaporates, the viscosity ofthe prepolymer solution on the substrate increases; less prepolymersolution is spun off at higher viscosities: therefore, coatings arethicker. When solutions of prepolymer in solvents with approximately thesame boiling point (such as mesitylene and diglyme) are spin coated, thesolution containing the solvent with the higher solvent viscositygenerally develops thicker coatings. Variations in film thickness fromprepolymer solutions of different concentrations indicate that as theprepolymer concentration increases from 40 to 70 percent by weight, thefilm thickness also increases.

Choice of solvent and the prepolymer concentration also affect thecoating quality. Prepolymer solutions in all of the solvents studied areobserved to produce good quality coatings, with somewhat less qualityobserved for coatings from solutions in diglyme. Prepolymer solutions ofmesitylene tend to exhibit highest quality coatings between 40 and 70percent by weight prepolymer for a wide range of film thicknesses (1-25microns). Highest coating quality is observed for prepolymerconcentrations of between 50 and 60 percent by weight.

Results indicate that film thickness increases as spin speed decreases.For low spin speeds of 1500 rpm and for high concentrations of 70percent by weight prepolymer, the order in thickness does not correlatewith the boiling point of the solvent. It is believed that the solutionviscosities are sufficiently high to overcome the effect of solventboiling points on film thickness. The order of film thickness observedfor o-xylene and n-butyl acetate at a spin speed of 1500 rpm, isbelieved to be a result of experimental error in the concentration ofprepolymer in n-butyl acetate. Furthermore, coatings from prepolymersolutions in n-butyl acetate and diglyme at concentrations greater than60 percent by weight prepolymer and for spin speeds of 1500 rpm areobserved to be of generally lower quality than those of other coatingsfrom these solvents. Film thickness increases with longer spread timesfor prepolymer solutions in mesitylene and diglyme. At spread timeslonger than 45 seconds, the increase in film thickness is not as largefor prepolymer solutions of the lower boiling solvents as for solutionsin higher boiling solvents. Shorter spread times generally result inbetter quality coatings.

The differences in thickness between R-2 and R-3 is believed to be aresult of differing molecular weight distributions of R-2 and R-3.

EXAMPLE 10 Planarity of a film of poly(TVE)

An aluminum disk having a surface roughness of 100-150 Å as measured bya profilemeter commercially available from Tencor, Inc. used accordingto the manufacturer's directions is coated withpoly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane] according to theprocedures used in Example 8 with mesitylene as solvent, at a 60 percentby weight concentration of prepolymer in solvent, and the cure ofExamples 1-9.

The planarity of the resulting coated disk is measured using theprofilemeter as for the disk and found to be 20-40 Å. This measurementindicates that polymers having perfluorocyclobutane groups are useful ascoatings to achieve planarization.

EXAMPLE 11 Planarity of a film ofpoly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane] over an aluminumconductor

Aluminum (Al) containing 1 weight percent copper (Cu) conductor linesare deposited on a silicon oxide substrate using standard techniquesused in microelectronics using the steps of:

(A) Cleaning the wafers in an oxygen plasma for 15 minutes using a LFE301C Barrel Plasma Etcher (commercially available from LFE PlasmaSystems) at a gas flow of 130 sccm oxygen, 260 watts, at 1 torr.

(B) Rinsing with ultra pure deionized water and spinning dry then 3rinses in ultra pure deionized water and another spinning dry.

(C) Depositing an approximately 2 μm metal layer of aluminum containing1 weight percent copper as an alloy by sputter depositon with an ion gunin an argon atmosphere using a Leybold 560 Box Coater (commerciallyavailable from Leybold-Heraeus Technologies, Inc.) having a DC (directcurrent) magnetron using 10 standard cubic centimeters (sccm) of argon,at a pressure of 5×10⁻⁴ mbars, a 500 V potential, 40 μmA current, for a1 minute duration to clean the surface and promote metal adhesionfollowed by a sputter process at 299 sccm argon, at a pressure of 2×10⁻³mbar, an alloy of aluminum with 1 pecent by weight copper as metalsource and 1500 watts for 60 minutes.

(D) Washing in a mixture of acetone and methanol, quickly dumping therinse to remove particulates, and drying at 100° C.

(E) Spin coating with a 4 μm layer of Shipley Microposit S1400-37Positive Photoresist (commercially available from Shipley Company, Inc.)for 2 sec. at 500 rpm with dynamic dispense, then spinning for 30 sec.at 2500 rpm to form a resist layer.

(F) Baking the coating 30 minutes at 100° C.

(G) Exposing the resist layer to determine the pattern of aluminum usinga Canon PLA-501FA aligner (commercially available from Canon USA, Inc.)using proximity mode and a high pressure mercury lamp with an exposureof 47.2 mJ/cm2 over aluminum measured at 405 nm.

(H) Developing the resist layer using Shipley Microposit 454 Developer(2 percent potassium hydroxide) (commercially available from ShipleyCompany, Inc.) by immersion at 18° C. for 90 sec.

(1) Flood exposing the resist layer using a Canon PLA-501FA aligner(commercially available from Canon USA, Inc.) using a high pressuremercury lamp with an exposure of 236 mJ/cm2 measured at 405 nm.

(J) Baking for 30 minutes in air at 120° C. such that the resist layerwithstands metal etching.

(K) Wet etching the aluminum layer at 45° C. for a period of 13.5 min.in a slightly agitated bath of phosphoric acid, 41.8 weight percent in50.1 percent water with 5.2 percent acetic acid and 2.9 percent nitricacid.

(L) Rinsing in ultra pure deionized water and drying.

(M) Stripping the resist by washing in acetone and mentanol.

(N) Oxygen plasma cleaning the resulting laminate for 15 minutes.

(O) Rinsing by dipping in ultrapure deionized water three times.

(P) Drying by spinning.

(Q) Dehydration baking at 200° C. for a period of 30 minutes.

Equipment used is that described in Examples 1-10 unless statedotherwise.

The lines have a height of 1.7 microns (μm) above the silicon oxidesurface as measured using a profilemeter, as in Example 10. A 4 μm thicklayer of poly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane] is coatedand cured over the silicon oxide and Al lines, using the procedure ofExample 6 and mesitylene as a solvent at 60 percent by weightconcentration of prepolymer in solvent, and the curing procedure ofExamples 1-9. The final cured film is observed to cover the surface suchthat the Al line protrudes above the planarity of the surface by 0.047μm as measured using the profilemeter. This corresponds to a degree ofplanarization (DOP) of 97%, and demonstrates the ability of the polymersto planarize large differences in topology as is important formicroelectronic applications such as multichip modules.

EXAMPLE 12 Composite ofpoly1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane] and glass fiber mat

Two plies of woven E glass (electrical glass) mat are cut (4"×5")(9×12.7 cm) and saturated withpoly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane] monomer. The clothis placed in: a 5 mil mold with Kapton™ polyimide film commerciallyavailable from DuPont de Nemours as release layers. The mold issandwiched between two 6"×6" (15.2×15.2 cm) aluminum 1/8" (0.32 cm)plates and pressurized to 15 tons gauge pressure (10,000 KPa) in ahydraulic press commercially available from Pasadena Hydraulics Inc.preheated to 180° C. and maintained at that temperature for 1 hour. Thetemperature of the press is then increased to 240° C. and held at thattemperature for 1 hour. The composite is cooled to room temperatureunder pressure, unmolded, and trimmed. The resulting composite is solid,light amber in color and flexible, with no visible voids.

EXAMPLE 13 Composite of prepolymerizedpoly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane] and glass mat.

The process of Example 12 is repeated using powderedpoly[1,1,1-tris(4-trifluoroethenyloxyphenyl)ethane] oligomers (heatedfor 1 hour at 160° C., cooled, and ground to a powder) and heating themold and plates preheated to 240° C. at 10,000 KPa for 1 hour (omittingthe 180° C. heating of Example 12). The resulting composite is cooled toabout 150° C. and removed from the press. The resulting composite issolid, slightly yellow in color, flexible, and has no visible voids.

EXAMPLES 14-15 Polystyrene microfibers having a coating ofpoly[4,4'-bis(trifluorovinyloxy)biphenyl]

Microfibers are prepared from a polystyrene resin commercially availablefrom The Dow Chemical Company under the trade designation Styron 685D(Example 14) and from syndiotactic polystyrene (Example 15), eachcontaining 2 weight percent poly4,4'-bis(trifluorovinyloxy)biphenyl]. Ahomogeneous melt blend results. A microfiber or a nonwoven mat ofmicrofibers is prepared by introducing an aromatic polymer resin in theform of powder or pellet into a hopper connected to an extruder. Theresin is melted in the extruder and supplied to a spinpack, through amolten polymer supplying line by a pump. The term "spinpack" refers toan assembly comprising a die nozzle having an orifice for a moltenpolymer and having a gas slot for melt-blowing the molten polymer, and aheater for keeping the die nozzle at a prescribed, uniform, temperatureof 220° C. The extruder, the spinpack, and the molten polymer supplyline also have a heater for melting a polymer or for keeping a polymerin a molten state.

A gas stream of hot air is introduced into the spinpack through a gasstream supplying line. In the spinpack, the molten polymer is forced outof an orifice of a nozzle of the spinpack into the co-current gas streamwhich attenuates the resin into fibers.

The fibers are collected in the form of a nonwoven mat. The moltenpolymer is forced out of an orifice of nozzle (die opening) and into thegas stream which is passed through gas slot. Conditions of thepreparation are given in Table 10.

                                      TABLE 10                                    __________________________________________________________________________                  polymer polymer flow                                                                          nominal gas                                                                           weight                                                                              weight percent                    Example                                                                            gas stream                                                                             temperature at                                                                        rate at flow rate at                                                                          percent                                                                             syndiotactic                      Number                                                                             temperature (°C.)                                                               nozzle (°C.)                                                                   nozzle (g/min)                                                                        nozzle (m/sec)                                                                        polystyrene                                                                         polystyrene                       __________________________________________________________________________    14   463      307     0.246   598     98     0                                15   462      307     0.294   597      0    98                                __________________________________________________________________________

The microfibers form a non-woven mass of fiber analogous to a cottonball. A cigarette lighter is held to each mass for a period of 15seconds. Neither of Examples 14 or 15 ignite, although some charring isobserved No dripping or burning is, however, observed. For comparison,non-woven masses of the polystyrene and syndiotactic polystyrene areformed without the poly[4,4'-bis(trifluorovinyloxy)biphenyl] and arefound to ignite readily.

The limiting oxygen index (LOI) ofpoly[4,4'-bis(trifluorovinyloxy)biphenyl] is determined by theprocedures of ASTM D-2863-87 to be 0.419 which is interpreted to meanthat the volume percent oxygen required to sustain combustion of thepoly4,4'-bis(trifluorovinyloxy)biphenyl] in an oxygen/nitrogenatmosphere is 41.9. NOTE: THESE NUMERICAL FLAME RATINGS ARE NOT INTENDEDTO REFLECT HAZARDS PRESENTED BY THESE OR ANY OTHER MATERIALS UNDERACTUAL FIRE CONDITIONS.

What is claimed is:
 1. An electronic device comprising a laminate ofhaving at least two layers at least one of which hereinafter referred toas the first or polymer layer, comprises a polymer having more than oneperfluorocyclobutane group, a backbone comprising perfluorocyclobutanegroups, linking structures and hydrocarbon containing groups; and isformed from at least one monomer having a structure represented byFormula I or II: ##STR2## wherein R represents an unsubstituted orinertly substituted group; each X is independently a bond or any groupwhich links R and a perfluorovinyl group; m+1 is the number of--X--CF═CF₂ units; n and n' are the number of G and G' groups,respectively; and G and G' independently represent any reactivefunctional groups or any groups convertible into reactive functionalgroupsand at least one outer layer, hereinafter referred to as thesecond layer, having a composition different from the first layercomprising silicon, silicon oxide, barium ferrite, a metal, asemiconductor, a polymer of different composition, ceramic, glass,paper, quartz or mixtures thereof.
 2. The electronic device of claim 1,which device is a hard disk drive, an optical disk, an integratedcircuit, a capacitor, a multichip module, a wave guide, a liquid crystaldisplay, magnetic tape, magnetic disk, optical recording device, opticalor magnetic reading or writing head, ring oscillator, optical filter,photo-voltaic device, thin film display, transducer, circuit board,microwave integrated circuit, microwave transmitter, microwave receiver,amplifier, charge-couple device, optical interconnect, optic sensor,solar cell, or combination thereof.
 3. The electronic device of claim 1wherein the polymer is an insulator in the device.
 4. The electronicdevice of claim 1 wherein R is an unsubstituted or inertly substitutedaromatic hydrocarbyl group; each X has at least one non-carbon atomselected from oxygen, sulfur, selenium, tellurium, silicon, boron,phosphorus and nitrogen between the perfluorovinyl group and R, X isattached to an aromatic carbon atom of R; m is an integer of from 1 to3; each of n and n' is independently an integer of from 1 to 4; and eachG and G' is independently selected from hydroxyl, carboxylic acid orester, thiocarboxylic acid or ester, acyl halide, isocyanate, acylazide, acetyl, trihaloacetyl, primary or secondary amine, sulfide,sulfonic acid, sulfonamide, ketone, aldehyde, epoxy, primary orsecondary amide, halo, nitro, cyano, anhydride, imide, cyanate, vinyl,ally, acetylene, trihalomethyl, alkoxy, alkyl groups, silicon-containinggroups, phosphorus-containing groups, boron-containing groups orcombinations thereof.
 5. The electronic device of claim 4 wherein thesecond layer comprises silicon or silicon oxide or a mixture thereof. 6.The electronic device of claim 4 wherein the second layer comprises ametal.
 7. The electronic device of claim 6 wherein the metal comprisesan alloy of chromium and at least one other metal.
 8. The electronicdevice of claim 4 wherein the second layer comprises a semiconductor. 9.The electronic device of claim 8 wherein the semiconductor comprisesgermanium arsenide, gallium arsenide or a combination thereof.
 10. Theelectronic device of claim 8, which device is a hard disk drive, anoptical disk, an integrated circuit, a capacitor, a multichip module, awave guide, a liquid crystal display, magnetic tape, magnetic disk,optical recording device, optical or magnetic reading or writing head,ring oscillator, optical filter, photo-voltaic device, thin filmdisplay, transducer, circuit board, microwave integrated circuit,microwave transmitter, microwave receiver, amplifier, charge-coupledevice, optical interconnect, optic sensor, solar cell, or combinationthereof.
 11. The electronic device of claim 10 wherein the polymer is adielectric insulator in the device.
 12. The electronic device of claim 4wherein the second layer comprises a polymer of different composition.13. The electronic device of claim 12 wherein the polymer of differentcomposition comprises synthetic fibers.
 14. The electronic device ofclaim 12 wherein the polymer of different composition comprises epoxyresin, polyimide, benzocyclobutane, polystyrene, polyamide,polycarbonate, polyester, perfluorocyclobutane ring-containing polymerof different composition from the first layer, or a combination thereof.15. The electronic device of claim 12, which device is a hard diskdrive, an optical disk, an integrated circuit, a capacitor, a multichipmodule, a wave guide, a liquid crystal display, magnetic tape, magneticdisk, optical recording device, optical or magnetic reading or writinghead, ring oscillator, optical filter, photo-voltaic device, thin filmdisplay, transducer, circuit board, microwave integrated circuit,microwave transmitter, microwave receiver, amplifier, charge-coupledevice, optical interconnect, optic sensor, solar cell, or combinationthereof.
 16. The electronic device of claim 15 wherein the polymer is adielectric insulator in the device.
 17. The electronic device of claim 4wherein the second layer comprises ceramic, paper or quartz, ceramic ora combination thereof.
 18. The electronic device of claim 4 wherein thesecond layer comprises glass.
 19. The electronic device of claim 4wherein the glass comprises comprises ceramitized glass.
 20. Theelectronic device of claim 4 wherein the second layer comprises bariumferrite.
 21. The electronic device of claim 4 wherein the the secondlayer is an optical fiber.